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Organic photodetectors (OPDs) hold immense promise for stretchable and wearable applications, but their photoactive films demonstrate brittleness, stiffness, and mechanical instability, posing challenges for future applications. Herein, the nanoconfinement effect is reported to substantially improve the stretchability and mechanical stability while reducing the stiffness of photoactive films, simultaneously maintaining the high light detection performance. The microstructure, mechanical properties, and photoelectric performance of the quaternary blend films with varying elastomer contents are thoroughly characterized. Additionally, the elastic modulus of quaternary blends can be accurately predicted by the Coran–Patel model. Cyclic tensile tests demonstrate enhanced mechanical stability, resulting in a specific detectivity of the quaternary blend with the nanoconfinement effect being 19 times higher than that of the ternary blend after 200 cycles. Overall, this study provides novel insights into constructing stretchable blend films for wearable electronics. [ABSTRACT FROM AUTHOR]

The incorporation of semi-crystalline polymers as additives with small-molecule organic semiconductors has emerged as a pioneering method for the alteration of crystallization processes, thin film morphologies, and charge carrier mobility within organic semiconductor matrices. In this paper, we utilize the intrinsic attributes of polyethylene oxide (PEO), acting as a semi-crystalline polymer additive, to modulate the crystallization, phase segregation and charge transport of 6,13-bis (triisopropylsilyl) pentacene (TIPS pentacene). To understand the synergistic effects between varying molecular weights (8, 100, 300 and 900 K) of PEO and the crystallization behavior of TIPS pentacene, we conducted a quantitative analysis of the films' relative crystallinity and crystallographic morphology employing X-ray diffraction (XRD) and optical microscopy. Our findings indicate that higher molecular weight PEOs (300K and 900K) exhibit reduced molecular chain activity, resulting in lower crystallinity at increased doping ratios. Furthermore, attributes such as a high dielectric constant and a substantial melting point, combined with favorable thermoplastic properties, predispose these films to a more susceptible phase separation within the crystalline matrix. Conversely, films with lower molecular weight PEOs (8 and 100 K) showed lesser impact from molecular chain dynamics, leading to enhanced crystal morphology, higher crystallinity, and improved charge carrier mobility by up to 11 times. This substantial enhancement underscores the potential of employing low molecular weight semi-crystalline polymers as additive agents in the development of advanced organic semiconductor devices. [ABSTRACT FROM AUTHOR]

Controlling the packing feature and film morphology of active layers is the precondition for achieving highly efficient organic solar cells (OSCs). The growth transition of donors and acceptors from solution to solid films plays an intrinsic role in shaping these features. In this study, two simple additives, cyanobenzene (CNB) and 1,4‐dicyanobenzene (DCNB), are presented to modulate the growth process of active layers to investigate the impact of growth behaviors on molecule packing quality, film morphology, and device performances. Both additives prolong the nucleation and growth period of active layers, resulting in improved molecular packing quality, domain purity, and crystallization. This optimization enhances charge extraction efficiency as well as reduces charge recombination losses. Consequently, devices based on D18:BTP‐eC9‐4F processed with additives obtain a 19.43% power conversion efficiency (PCE). Furthermore, a PCE of 14.35% is achieved for bladed‐coated organic solar modules on 5 cm × 5 cm substrates. These findings underscore the importance of growth processes on film quality and illustrate their fundamental relationship, which promises further advancements in OSC technology. [ABSTRACT FROM AUTHOR]

Semitransparent organic photodetectors (ST‐OPDs) show immense promise for integration into optoelectronic devices, offering adjustable absorption and see‐through functionalities. However, achieving high‐performance ST‐OPDs remains challenging, necessitating a delicate balance of low dark current density, high external quantum efficiency, and optimal visible light transmission. Here, a strategy is presented using anode interfacial materials (AIMs) as the donor and narrow bandgap non‐fullerene acceptors (NFAs) to formulate the donor: acceptor light‐sensitive layer. Critical to the approach is the incorporation of 1,8‐diiodooctane during film processing, enabling the formation of morphology with an NFA molecular crystal network embedded within the donor polymer matrix. This optimized morphology substantially boosted device external quantum efficiency and reduced dark current under reverse bias, yielding a remarkable special detectivity of over 1013 Jones at 840 nm under a bias of −0.1 V. ST‐OPDs are achieved with detectivity surpassing 1012 Jones and notable average visible transmittance of over 50%. These findings highlight the potential of AIM:NFA combinations for high‐efficiency ST‐OPDs by finely controlling morphology through multiple length scales, opening doors for various applications in transparent electronics and beyond. [ABSTRACT FROM AUTHOR]

Abstract Goals of high efficiency, morphological analysis, and the ability to produce organic solar cell (OSC) sub‐modules using halogen‐free solvents are demanding. In this study, a robust conjugated polymer with thienothiophene π‐spacer with pendant alkyl side chain (NapBDT‐C12) was synthesized and used to fabricate sub‐modules. Excellent efficiencies were demonstrated by a NapBDT‐C12 integrated ternary blend, which was used to produce stable small‐area‐to‐sub‐module devices using O‐xylene. The efficiency of the NapBDT‐C12 added small‐area ternary devices (PM6:NapBDT‐C12:L8‐BO) was 18.71%. Owing to the controlled homogeneity of the blend with favorable nanoscale film morphology, enhanced carrier mobilities, and exciton dissociation/splitting properties, contributed to the efficiencies of small‐area‐to‐sub‐module OSCs. Moreover, a 55 cm2 sub‐module with an efficiency of 14.69% was accomplished by bar coating using O‐xylene under ambient conditions. This study displays the potential of a ternary blend based OSC device to produce high efficiency scalable sub‐modules at ambient conditions.

Film morphology of donor:acceptor blend layers plays a critical role in photon-to-current efficiency and dark/noise current of organic photodetectors (OPDs). One effective approach to manipulate crystallization and mesoscale phase separation of such blend layers is sequential casting (SC). However, the guiding strategies to control the morphology and the impacts on OPD performance of the SC films remain elusive, as the film structural evolution during SC is different from conventional blend casting (BC). Here, a refined fibrillar multiphase morphology is demonstrated by SC in an NT812:IEICO-4F blend film, where the high-quality IEICO-4F crystallites infiltrate the robust NT812 fibril network from the surface to the bulk. Such a morphology leads to improved charge generation and collection, reduced trap states, and enhanced charge block capability of resultant device, enabling simultaneous achievement of high external quantum efficiency and low dark/noise current. A maximum special detectivity of 5 × 1013 Jones is achieved at 860 nm under –0.1 V, which is among the highest detectivities for vis-to-NIR OPDs. The linear dynamic range and response speed are also improved. Such enhancements are parallelly observed from OPD devices based on other blend systems with similar fibrillar refinement, which provides guidelines for film structure manipulation towards high OPD performance.

Meniscus‐guided coating (MGC) is a promising method that offers predictable fabrication of highly crystalline thin films. For the integration of molecular semiconductors into large‐area electronic devices with high efficiency and reliability, homogeneous and highly ordered film morphologies are required. The solution processing of such defect‐free film structures requires comprehensive understanding of the complex relationship between molecular crystallization, fluid dynamics, and meniscus shape. In this work, the role of the meniscus shape on fluid dynamics in the coating bead and the crystallization process of the low molecular weight semiconductor 6,13‐bis(triisopropylsilylethynyl)pentacene (TIPS‐pentacene) during zone‐casting is systematically investigated. Depending on meniscus shape and coating velocity, four morphological subregimes are found: stick‐slip morphology, unidirectional homogenous crystal stripes, spherulitic morphology, and directional branched morphology; of which the second exhibits the highest crystallinity with a reduced trap density in the thin film, resulting in improved saturation and effective mobilities in field‐effect transistors (FET). Numerical simulation of fluid dynamics explains the observed morphological trends, which are correlated with the electrical behavior of the devices. This work provides a fundamental basis for upscaling MGC methods for the application of functional thin films. [ABSTRACT FROM AUTHOR]

The progress of stretchable and wearable photovoltaics relies heavily on intrinsically stretchable active layer films. Nevertheless, there is a paucity of research clarifying the connections between their microstructure, performance, and their adaptation to large strain in polymer electronic films. The current study utilizes multiple synchrotron X‐ray scattering methods to collectively examine the correlations between morphology and stretchability, as well as the microstructural evolution induced by stretching in three sample cases of highly stretchable ternary blend films. These blends contain over 30% by weight of a polymer elastomer, such as styrene‐ethylene‐butylene‐styrene block copolymer, integrated into the high‐performance polymer:nonfullerene small molecule mixture. Specifically, the real‐time microstructural changes of these durable organic photovoltaic films with elastomers are monitored when subjected to tensile stretching through in situ synchrotron X‐ray scattering. The experiments demonstrate that polymeric elastomers can effectively lower the degree of crystallinity in films and deform the crystallites of semiconductor molecules. The elastomeric component aids in stress dispersion during stretching, thereby improving the microstructural durability of blend films. This study provides new recommendations for advancing stretchable organic optoelectronic devices. [ABSTRACT FROM AUTHOR]

Controlling the phase separation and domain purity of organic semiconductors to form well‐developed nanoscale morphology optimization in the bulk‐heterojunction active layer is critical yet challenging for building high‐performance organic photodetectors. Herein, an effective morphology controlling method by applying a small molecule IC‐Br as the solid additive is demonstrated, which can effectively restrict the overmix of the PTzBI‐Si:IEICO‐4F in the process of film formation. The film processed with IC‐Br formed well‐developed nanoscale phase separation with bi‐continuous interpenetrating networks, which exhibited enhanced π–π stacking and the improved domain purity of the IEICO‐4F phase, resulting in a significant decrease in the density of the trap state compared to the pristine film. Consequently, the device processed with IC‐Br additive enabled a high specific detectivity of 3.8 × 1013 Jones at 860 nm under −0.1 V associated with the improved linear dynamic range and response speed, indicating the strong visible‐to‐near infrared detecting capability and potential for practical applications. The morphology optimization strategy established in this work may offer unprecedented opportunities to build state‐of‐the‐art OPDs. [ABSTRACT FROM AUTHOR]

The aim of this work was to develop and characterise nanocomposite thin films containing silver nanoparticles (AgNPs), as wound dressings and antifungal materials, using a green process for the nanoparticles’ synthesis and a single step procedure for the preparation of the nanocomposite films. To this end, polyphenol-rich extracts obtained from kiwi peels, an agri-food industrial by-product, were used as a reducing agent of silver nitrate salt. The AgNPs were let form within the film-forming solution, which was composed by low acyl gellan gum and a plasticising agent (glycerol or PEG 400 g/mol) and the corresponding nanocomposite films were deposited by the solvent casting technique. The plasticising agent affected the AgNPs distribution within the films, as observed by SEM and EDS analyses, and consequently their tensile behaviour. In specific, AgNPs act as stress intensifiers in the presence of glycerol, whereas they act as film reinforcement with PEG400. However, both glycerol-plasticised and PEG400-plasticised films exhibited similar antifungal efficacy against 16 clinical isolates of 5 different Candida spp (C. albicans, C. lusitaniae, C. haemulonii, C. krusei and C. glabrata). Globally, the present study provides a green and single-step procedure to develop nanocomposite films embedding AgNPs obtained by in situ reduction of silver ions with polyphenol-rich extracts.

Manganese-containing silicon–carbon films are formed by electrochemical deposition from solutions based on hexamethyldisilazane and methanol on dielectric substrates with contact metallization of copper. The manufactured structures show a gas-sensitive response to carbon monoxide, sulfur dioxide, and methane molecules. It is established that the manufactured structures have a selective gas sensitivity to 1 ppm of carbon monoxide at an operating temperature of 150°C. The kinetics of gas adsorption is described using the Elovich model. It is shown that at the initial moment the adsorption of methane and sulfur dioxide is represented by monomolecular adsorption. Scanning electron microscopy shows that the structure of the samples is multiphase and is characterized by the presence of the hexagonal 6H and rhombohedral 15R phases of silicon-carbide polytypes. The presence of the Si–C bond responsible for the presence of the amorphous phase of silicon carbide is also found. It is shown that under the influence of gases, a change in the structure of the samples occurs, which, in particular, manifests itself in a change in the position of the D and G peaks, the appearance of a phase of disordered graphite, as well as in the aggregation of crystallites with a change in size from 200 to 300 nm. [ABSTRACT FROM AUTHOR]

Organic electrochemical transistors (OECTs) based on conducting polymers have attracted significant attention in the field of biosensors. PEDOT:PSS and polyaniline (PANI) are representative conducting polymers used for OECTs. While there are many studies on PEDOT:PSS, there are not so many reports on PANI-based OECTs, and a detailed study to compare these two polymers has been desired. In this study, we investigated the fabrication conditions to produce the best performance in the OECTs using the above-mentioned two types of conducting polymers. The two main parameters were film thickness and film surface roughness. For PEDOT:PSS, the optimal conditions for fabricating thin films were a spin-coating rate of 3000 rpm and a DI water immersion time of 18 h. For PANI, the optimal conditions were a spin-coating rate of 3000 rpm and DI water immersion time of 5 s, and adding dodecylbenzenesulfonic acid (DBSA) was found to provide better OECT performances. The OECT performances based on PEDOT:PSS were superior to those based on PANI in terms of conductivity and transconductance, but PANI showed excellence in terms of film thickness and surface smoothness, leading to the good reproducibility of OECT performances. [ABSTRACT FROM AUTHOR]

Photocatalytic hydrogen evolution through water splitting offers a promising way to convert solar energy into chemical energy. Covalent triazine frameworks (CTFs) are ideal photocatalysts owing to its exceptional in‐plane π‐conjugation, high chemical stability, and sturdy framework structure. However, CTF‐based photocatalysts are typically in powder form, which presents challenges in catalyst recycling and scale‐up applications. To overcome this limitation, we present a strategy for producing CTF films with excellent hydrogen evolution rate that are more suitable for large‐scale water splitting due to their ease of separation and recyclability. We developed a simple and robust technique for producing CTF films on glass substrates via in‐situ growth polycondensation, with thicknesses adjustable from 800 nm to 27 μm. These CTF films exhibit exceptional photocatalytic activity, with the hydrogen evolution reaction (HER) performance reaching as high as 77.8 mmol h−1 g−1 and 213.3 mmol m−2 h−1 with co‐catalyst Pt under visible light (≥420 nm). Additionally, they demonstrate good stability and recyclability, further highlighting their potential in green energy conversion and photocatalytic devices. Overall, our work presents a promising approach for producing CTF films suitable for a range of applications and paves the way for further developments in this field. [ABSTRACT FROM AUTHOR]

This work discusses how some of Schrödinger's latest innovations in digital chemical simulation accelerate materials discovery in displays. We will describe simulation tools to explore OLED materials degradation, film morphology from evaporative and solution molecular deposition, spectral predictions for light‐emitting processes, and excited state energy transfer. [ABSTRACT FROM AUTHOR]

The new polymer, poly[1-(5-(4,8-bis(4-chloro-5-(2-ethylhexyl)thiophen-2-yl)-6-methylbenzo[1,2-b:4,5-b′]dithiophen-2-yl)-4-fluorothiophen-2-yl)-5,7-bis(2-ethylhexyl)-3-(4-fluoro-5-methylthiophen-2-yl)benzo[1,2-c:4,5-c′]dithiophene-4,8-dione] comprising PFBDB–TCl–(EH) was designed and synthesized for fabrication of non-fullerene organic solar cells application. The PFBDB–TCl–(EH) was synthesized by Stille polymerization. PFBDB–TCl–(EH) blended with IT-4F and Y7 exhibited an efficiency of 5.03% and 9.10%. By contrast, PFBDB–TCl–(EH):SiCl–BDT:Y7-based ternary device exhibited best efficiency of 15.10%, open-circuit voltage (Voc) of 0.83 V, a short-circuit current density (Jsc) of 27.68 mA/cm2, and fill factor (FF) of 65.25%, respectively. This results indicated the PFBDB–TCl–(EH) exhibited excellent compatibility with the host blend SiCl–BDT:Y7 and tended to enhance miscibility and formed cascade energy levels. Newly synthesized π conjugated polymer PFBDB-TCl-(EH) used as ternary device in non-fullerene organic solar cells. Due to presence of halogen atoms, PFBDB-TCl-(EH), deeper HOMO energy levels were observed in − 5.58 eV. The power conversion efficiency also improved from binary device with 9.10% to ternary device with 15.10%. [ABSTRACT FROM AUTHOR]

Reactive multilayer systems are nanostructures of great interest for various technological applications because of their high energy release rate during the self‐propagating reaction of their components. Therefore, many efforts are aimed at controlling the propagation velocity of these reactions. Herein, reactive multilayer systems of Al/Ni in the shape of free‐standing foils with a wavelike surface morphology prepared by using sacrificial substrates with well‐aligned waves are presented and the propagation of the reaction along different directions of the reproduced waves is analyzed. During the ignition test, the propagation front is recorded with a high‐speed camera, and the maximum temperature is measured using a pyrometer. The propagation of the reaction is favored in the direction of the waves, which points out the influence of the anisotropy generated by this morphology and how it affects the propagation dynamics and the resulting microstructure. Furthermore, compared to their counterparts fabricated on flat substrates, these reactive multilayers with wavelike morphology exhibit a remarkable reduction in the propagation velocity of the reaction of about 50%, without significantly affecting the maximum temperature registered during the reaction. [ABSTRACT FROM AUTHOR]

We have entered a paradigm-changing era in the way chemists innovate. Many fields, such as automotive engineering and particle physics, rely today on accurate simulation before experimentation. In recent years, chemistry has entered a new phase of chemical solution design powered by a rich set of physics-based and augmented intelligence capabilities. This talk will present select case studies illustrating some of our latest physics-based simulation technology for developing and optimizing OLED materials. We will also introduce an enterprise informatics platform (LiveDesignTM) focused on chemical discovery, enabling multidisciplinary teams to amplify their development cycle with collaboration on a global scale. [ABSTRACT FROM AUTHOR]

Organic electrochemical transistors (OECTs) based on conducting polymers have attracted significant attention in the field of biosensors. PEDOT:PSS and polyaniline (PANI) are representative conducting polymers used for OECTs. While there are many studies on PEDOT:PSS, there are not so many reports on PANI-based OECTs, and a detailed study to compare these two polymers has been desired. In this study, we investigated the fabrication conditions to produce the best performance in the OECTs using the above-mentioned two types of conducting polymers. The two main parameters were film thickness and film surface roughness. For PEDOT:PSS, the optimal conditions for fabricating thin films were a spin-coating rate of 3000 rpm and a DI water immersion time of 18 h. For PANI, the optimal conditions were a spin-coating rate of 3000 rpm and DI water immersion time of 5 s, and adding dodecylbenzenesulfonic acid (DBSA) was found to provide better OECT performances. The OECT performances based on PEDOT:PSS were superior to those based on PANI in terms of conductivity and transconductance, but PANI showed excellence in terms of film thickness and surface smoothness, leading to the good reproducibility of OECT performances.

The ternary phase diagram based on cellulose (cellulose polymer/mixed solvents/Water (non-solvent)) system has been measured at 30 °C for two sources of cellulose. Cellulose synthesized from fibers of cotton and olive significantly influences the behavior of the crystallization index, which can cause changes during the film formation process. The differences can be explained by the presence of amorphous areas linked to a higher disorder, which is highlighted by the X-ray diffraction analysis XRD (crystallinity rate was 15.6% versus 47.4% for acetylated cellulose). The experimental analysis was carried out on the coexisting phases and the determination of binodal curve. The cellulose film was formed based on the equilibrium diagram to control the structure, which showed some dependence between the composition data and the binary interaction parameters in order to achieve liquid–liquid phase separation. This system required a large amount of water (15–90 wt.% water) to affect the porous and fibrous structure of the film. Olive cellulose films with lower crystallinity have smaller diameter (38 nm), they can swells faster and their solubility increases more, unlike acetate cellulose (56 nm). It can be said that the solvent diffusion is greater in the amorphous domains due to their higher disorder resulting in easy accessibility. [ABSTRACT FROM AUTHOR]

P3HT stands out from numerous polymer donors owing to the merits of low cost and high scalability of synthesis. However, the photovoltaic performance of P3HT-based blends lags significantly behind the state-of-the-art systems, especially for all-polymer solar cells (APSCs) that generally show efficiency of around 3%–4% due to the lack of matched polymer acceptors. Herein, a polymer acceptor, named IDTBTC8-CN, was designed and synthesized with indacenodithiophene (IDT) and mono-cyano (CN)-substituted benzothiadiazole (BT-CN) as building blocks. Introducing a CN group endowed the polymer with decreased bandgap, and apparent n-type charge transport character despite the relatively high energy levels. Additionally, IDTBTC8-CN showed largely improved miscibility with P3HT, compared with that of BT-based control polymer IDTBTC8. The high miscibility between P3HT and IDTBTC8-CN as well as the amorphous aggregation behavior of IDTBTC8-CN enabled a broad manipulation room for the blend film to acquire favorable morphology. Eventually, a champion efficiency of 8.30% was achieved, in sharp contrast to that of the IDTBTC8-based system (1.21%). Such efficiency is a new record for P3HT-based APSCs reported so far. Moreover, P3HT:IDTBTC8-CN blend film also exhibited excellent mechanical robustness. This study implies the guidance of molecular design of the polymer acceptors and morphology control for P3HT-based APSCs. [ABSTRACT FROM AUTHOR]

This work presents a facile sol–gel method for the deposition of ZnO and ZnO:Mg films. The films are spin coated on silicon and quartz substrates. The impact of magnesium concentrations (0, 0.5, 1, 2 and 3 wt%) and post-annealing treatments (300–600 °C) on the film's structural, vibrational and optical properties is investigated. Undoped ZnO films crystallize in the wurtzite phase, with crystallite sizes ranging from 9.1 nm (300 °C) to 29.7 nm (600 °C). Mg doping deteriorates the film crystallization and shifting of 002 peak towards higher diffraction angles is observed, indicating the successful incorporation of Mg into the ZnO matrix. ZnO:Mg films (2 wt%) possess the smallest crystallite size, ranging from 6.2 nm (300 °C) to 25.2 nm (600 °C). The highest Mg concentration (3 wt%) results into a segregation of the MgO phase. Lattice constants, texture coefficients and Zn–O bond lengths are discussed. The diminution of the c lattice parameter is related to the replacement of Zn2+ by Mg2+ in the ZnO host lattice. The vibrational properties are studied by Fourier transform infrared (FTIR) spectroscopy. IR lines related to Mg–O bonds are found for ZnO:Mg films with dopant concentrations of 2 and 3 wt%. The optical characterization showed that the transmittance of ZnO:Mg thin films increased from 74.5% (undoped ZnO) to about 89.1% and the optical band gap energy from 3.24 to 3.56 eV. Mg doping leads to a higher refractive index compared to undoped ZnO films. The FESEM (field emission scanning electron microscopy) technique is used for observation of the surface morphology modification of ZnO:Mg films. The doped ZnO films possess a smoother grained surface structure, opposite to the wrinkle-type morphology of undoped sol–gel ZnO films. The smoother surface leads to improved transparency of ZnO:Mg films. [ABSTRACT FROM AUTHOR]

The sol-gel process for making thin-film oxide materials is a low-cost and versatile way of creating nanostructures. This method provides a uniform distribution of elements of multicomponent systems over the surface of various solids. The thickness and morphology of the surface of oxide films are largely determined by the composition, structure, and processes occurring in the sols from which the films are obtained. The selection of precursors is essential in this method to acquire the desired composite oxide materials. In this paper, we present an overview of the results of studies on the sol-gel production of thin-film oxide materials based on SiO2–ExOy (E = a rare earth element (REE), Sn, Mn, Co, Ni, Ca, P), TiO2–ExOy (E = Si, Sn, Co, Ni), SnO2–ExOy (E = In, Sb, Ce), and ZrO2. In the main part of the work, we consider sol-gel processes (hydrolysis, polycondensation, complex formation) involving tetraethoxysilane, tetrabutoxytitanium, antimony(III), and tin(II, IV) acetylacetonate complexes, as well as polynuclear zirconium(IV) clusters. We explore the processes of obtaining a sol, leading to its film-forming ability, the composition of micelles, the size of colloidal particles, and the change in the composition of micelles when an additive is introduced to the tetraethoxysilane-based sol. We discuss the effect of adding salts of various natures, organic ligands, and solvents on the time stability of sols. We then consider the effect of the hydrolyzing ability of doubly charged nickel, manganese, and cobalt cations on the rate of hydrolysis and polycondensation of tetraethoxysilane. Based on the studies mentioned above, we propose a general technological approach for creating sols that are resistant to film formation, using the example of tetraethoxysilane and tetrabutoxytitanium sols. We consider the relationship between the network structure of a tetraethoxysilane sol and the network structure of oxide films by the example of SiO2–CeO2, SiO2–NiO, SiO2–Mn2O3, and SiO2–Co3O4. The effect of the rate of thermal treatment of gels on the morphology of oxide films is also studied. [ABSTRACT FROM AUTHOR]

Organic solar cells (OSCs) have drawn lots of attention because of their rapid development and great potential in large‐area flexible electronics. Recently, volatile solid additives have been widely used in optimizing morphologies of active layers and improving device performances for nonfullerene (NF)‐based OSCs. Most solid additives, however, still suffer severe problems such as unsuitable volatile temperatures and requirement of extra solvent additives. Herein, a new solid additive 2,7‐dibromo‐9,9‐dimethylfluorene (DBDMF) with a high crystallinity and suitable volatile temperature as an additive for NF‐based OSCs is designed. DBDMF can suppress the overaggregation of the nonfullerene acceptors (NFAs) and improve the material rearrangements after thermal annealing because of the good miscibility with the NFAs. As a result, DBDMF‐treated OSC devices display more favorable film morphologies and phase separation, well‐balanced charge mobilities, higher electron transfer rates, and better device stability. Consequently, the PM6:BTP‐BO‐4F binary system shows an outstanding power conversion efficiency of 17.2% from 15.3% with a simultaneous increase in the fill factor from 71.4 to 77.1%. Furthermore, DBDMF has been applied to other two active layers, manifesting the general applicability. This study demonstrates a feasible and promising approach to develop volatilizable solid additives for improving performance and stability of NF‐based OSCs. [ABSTRACT FROM AUTHOR]

Herein, we design and characterize 9-heterocyclic ring non-fullerene acceptors (NFAs) with the extended backbone of indacenodithiophene by cyclopenta [2,1-b:3,4-b'] dithiophene (CPDT). The planar conjugated CPDT donor enhances absorption by reducing vibronic transition and charge transport. Developed NFAs with different end groups shows maximum absorption at approximately 790–850 nm in film. Because of the electronegative nature of the end-group, the corresponding acceptors showed deeper LUMO energy levels and red-shifted ultraviolet absorption. We investigate the crystallinity, film morphology, surface energy, and electronic as well as photovoltaic performance. The organic photovoltaic cells using novel NFAs with the halogen end groups fluorine or chlorine demonstrate better charge collection and faster exciton dissociation than photovoltaic cells using NFAs with methyl or lacking a substituent. Photovoltaic devices constructed from m-Me-ITIC with various end groups deliver power conversion efficiencies of 3.6–11.8%. [ABSTRACT FROM AUTHOR]

Doped (with GaCl3), undoped ZnO and ITO/ZnO:Ga nanostructured thin films are synthesized using the spray pyrolysis method. The doped ZnO thin films are synthesized at the atomic ratio of Ga/Zn added in the starting solution fixed at 1, 2, 3, and 5. Gallium-doped ZnO films synthesized on glass/ITO substrates are annealed at 4500C in different environments: vacuum, oxygen, and hydrogen. X-ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM), and current–voltage (I–V) measurements are applied to characterize the structural properties, composition, surface morphology, and electrical properties of ZnO:Ga nanostructured thin films. X-ray diffraction analysis shows that ZnO:Ga films deposited on glass substrates have a dense and homogeneous surface with a hexagonal structure. The ZnO:Ga films deposited on glass/ITO substrates are composed of two phases, namely, hexagonal ZnO and cubic ITO. The I–V characteristics show the presence of good ohmic contacts between Al and In metals and ZnO:Ga thin films regardless of the nature of the substrate and the annealing atmosphere.Au fost sintetizate straturi subțiri nanostructurate ZnO atât dopate cu (GaCl3), cât și nedopate, precum și straturi de ITO/ZnO:Ga, folosind metoda prin pulverizare cu piroliză. Straturile subțiri de ZnO dopate au fost sintetizate la raportul atomic Ga/Zn adăugat în soluția inițială fixă la 1, 2, 3 și 5 Straturile nanostructurate de ZnO dopate cu Ga obținute pe substraturi de sticlă/ITO au fost tratate termic la 450℃ în diferite medii: vid, oxigen și hidrogen. S-au realizat măsurătorile de difracție cu raze X (XRD), spectroscopie cu raze X cu dispersie energetică (EDX), microscopie cu forță atomică (AFM), curent-tensiune (I-V) pentru a caracteriza proprietățile structurale, compoziția, morfologia suprafeței și proprietățile electrice ale straturilor subțiri de ZnO:Ga. Analiza XRD arată că stratul de ZnO:Ga depus pe substratul de sticlă are o suprafață densă și omogenă cu structura hexagonală. Stratul de ZnO:Ga depus pe substraturi de sticlă/ITO indică două faze, acestea fiind ZnO hexagonal și ITO cubic. Caracteristica I-V prezintă contacte ohmice bune între metalele Al, In și straturile subțiri de ZnO:Ga, indiferent de natura substratului și de atmosfera de tratare termică.

In this work, five polythiophene derivatives were synthesized through electrochemical copolymerization of 3,3-bis(bromomethyl)-3,4-dihydro-2 H -thieno[3,4- b ] (Deng et al., 2023; Li et al., 2020) [1,4]dioxepine (ProDOT-Br) and 3,3-dimethyl-3,4-dihydro-2 H -thieno[3,4- b ] (Deng et al., 2023; Li et al., 2020) [1,4]dioxepine (ProDOT-Me) at different mass ratios. DFT results prove that the layer spacing of conjugated blocks was increased from 5.94 Å for PProDOT-Me to 8.89 Å for PProDOT-Br due to the introduction of Br atom into side chain. And, the diverse film morphologies, such as fibre shape, cellular shape, flat shape, etc, were obtained by changing Br content in polymer. Additionally, through optimizing Br content, PBM(1,2) achieved enhanced electrochromic properties relative to two reference polymers [PProDOT-Br and PProDOT-Me], such as high optical contrast (Δ T = 76 %), fast response time (0.5 s), high transparency, and good stability. Finally, the flexible electrochromic device (8 cm × 4 cm) based on PBM(1,2) was constructed, which achieves rapid color change from purple to transparent blue. The results indicate that introducing various contents of Br atom into side chain is an effective strategy for regulating molecular microstructure and optimizing electrochromic properties of conjugated polymers. [Display omitted] • A series of Br modified polythiophene derivatives were prepared by electrochemical method. • Br in side chain could regulate the microstructure of conjugated polymer. • PBM(1,2) achieves high optical contrast (Δ T = 76 %), fast response time (0.5 s), and good stability. [ABSTRACT FROM AUTHOR]

Reversibility and durability have become new bottlenecks for conjugated polymers to realize "stretchable" semiconducting devices. Therefore, the correlation between microstructure and mechanical properties requires explicit delineation. Herein, the deformation and fracture mechanisms of DPP-TVT (poly [2,5-bis(4-decyl tetradecyl) pyrrolo [3,4-c]pyrrole-1,4-(2H, 5H)-dione-(E)-1,2-di (2,2′-bithiophen-5-yl)ethene) films with various degree of lamellar order were investigated from microscopic view. In the medium ordered films, the lamellae and amorphous phase cooperate to form the fibrous network structure in respond to tensile deformation. When recovered, this fibrous network could deform and being compressed, providing an efficient stress transfer pathway to accommodate the residual strain. Therefore, the medium ordered films did not form cracks even under 100 cycles of 50 % strain. However, in near-amorphous films, the uniformly aligned chains in stretched films were difficult to reorient under compression, resulting in the formation of large wrinkles and poor fatigue resistance. And the highly ordered films generate cracks both under single and cyclic stretch due to lacking of stress dissipation pathways. This study lays the groundwork for enhancing the mechanical robustness of conjugated polymer films. [Display omitted] • Displayed the microstructure change during stretch in conjugated polymer film. • Investigated the relation between morphology and deformation mechanism. • Proposed that medium degree of order is favorable for fatigue behavior. [ABSTRACT FROM AUTHOR]

Fluorene is a blue luminous moiety attracting wide attention due to its all kinds of high technology applications, and the rigid biphenyl planar structure of fluorene makes it prone to crystalize and form intermolecular aggregation, which means that emitting colors and carrier mobilities of fluorene-based fluorescence emitters are highly adjustable by the modification of 9,9-position of fluorene with different pendant moieties. In this regard, fluorene (F) is used as a model blue emitter, and different pendant groups of n-butyl, p-hexyloxy phenyl and 2,4,6-triphenyl-1,3,5-triazine are introduced into the 9-position of fluorene to produce four topology-varied organic light-emitting emitters, namely 9,9-dibutyl-fluorene (DBF), 9,9-bis-(4-butoxy-phenyl)-fluorene (BOPF), 2-{4-[9-(4-hexyloxy-phenyl)-fluoren-9-yl]-phenyl}-4,6-diphenyl- (Chan et al., 2017; Wex and Kaafarani, 2017; Liang et al., 2019) [1,3,5]triazine (FTRZ) and 2,4,6-tris-{4-[9-(4-hexyloxy-phenyl) -fluoren-9-yl]-phenyl}- (Chan et al., 2017; Wex and Kaafarani, 2017; Liang et al., 2019) [1,3,5]triazine (pTFTRZ). The general differences in thermal stability, photoluminescence quantum efficiency, emission wavelength, electrochemical energy levels, crystal structure, carrier mobility and film morphology of the emitters are experimentally and theoretically studied to correlate their structures with optoelectronic properties. FTRZ and pTFTRZ solid powder show higher melting points of 186 °C and 122 °C. The highest occupied molecular orbit energy levels are −5.95 eV for F , −6.02 eV for DBF , −6.11 eV for BOPF and −6.23 eV for FTRZ , and the corresponding lowest unoccupied molecular orbits energy levels are −2.03 eV for F , −2.19 eV for DBF , −2.25 eV for BOPF and −2.55 eV for FTRZ. When compared with the other three emitters, due to the enhanced intramolecular charge transfer caused by the electron-deficient 2,4,6-triphenyl-1,3,5-triazine group, FTRZ showed significant redshifts of 75 nm in their emission spectrum of solution, and the photoluminescence quantum efficiencies of FTRZ and pTFTRZ solid powder were also decreased to less than 1%. The single crystal of F is an orthorhombic system while those of DBF , BOPF and FTRZ are all monoclinic system. The electron and hole mobilities of the thin solid films were decreased in the order of FTRZ , BOPF and pTFTRZ , and thin solid film of FTRZ showed the highest electron mobility of 10−4cm2/V • s at an electric field of 4 × 104 V/cm. The RMS values corresponding to root-mean-square averages of the height deviations of film measured by atomic force microscopy are 4.32 nm for BOPF , 1.11 nm for FTRZ , 11.8 nm for pTFTRZ. The FTRZ films exhibited smaller RMS and smooth surface morphology beneficial for the carrier mobility relative to those of BOPF and pTFTRZ. The pendant groups of n-butyl, p-hexyloxy phenyl and 2,4,6-triphenyl-1,3,5-triazine in the 9-position of fluorene adjust the general optoelectronic properties of the obtained emitters in a wide range. • FTRZ and pTFTRZ solid powders show higher melting points of 186 °C and 122 °C; • The carrier mobilities of the FTRZ , BOPF and pTFTRZ thin solid films decreased in turn; • The PLQYs of FTRZ and pTFTRZ solid powders decreased to less than 1%; • The single crystal of F is an orthorhombic system while those of DBF , BOPF and FTRZ are all monoclinic system; • The FTRZ films exhibited smaller RMS beneficial for the improved carrier mobilities. [ABSTRACT FROM AUTHOR]

Molecular aggregation and crystallization during film coating play a crucial role in the realization of high‐performing organic photovoltaics. Strong intermolecular interactions and high solid‐state crystallinity are beneficial for charge transport. However, fast crystallization during thin‐film drying often limits the formation of the finely phase‐separated morphology required for efficient charge generation. Herein, the authors show that twisted acceptor‐donor‐acceptor (A‐D‐A) type compounds, containing an indacenodithiophene (IDT) electron‐rich core and two naphthalenediimide (NDI) electron‐poor units, leads to formation of mostly amorphous phases in the as‐cast film, which can be readily converted into more crystalline domains by means of thermal annealing. This design strategy solves the aforementioned conundrum, leading to an optimal morphology in terms of reduced donor/acceptor domain‐separation sizes (ca. 13 nm) and increased packing order. Solar cells based on these acceptors with a PBDB‐T polymer donor show a power conversion efficiency over 10% and stable morphology, which results from the combined properties of desirable excited‐state dynamics, high charge mobility, and optimal aggregation/crystallization characteristics. These results demonstrate that the twisted A‐D‐A motif featuring thermally‐induced crystallization behavior is indeed a promising alternative design approach toward more morphologically robust materials for efficient organic photovoltaics. [ABSTRACT FROM AUTHOR]

Blade‐coating which is compatible with roll‐to‐roll (R2R) fabrication has been considered a promising technology for the large‐scale production of organic solar cells (OSCs). Despite the rapid increase in power conversion efficiency (PCE) of the devices, most processing solvents are still halogenated, which is a key issue that needs to be addressed urgently in commercialized manufacturing. In this work, targeted strategies are explored for the preparation of efficient OSCs via combining the nonhalogenated solvent toluene (TL) with blade‐coating. Based on the in situ UV–vis absorption, grazing‐incidence wide‐angle X‐ray scattering, and device performance measurements, the subtle relationship between processing solvents, film morphology, and properties is successfully established. The PM6:BTP‐eC9 blend film prepared by this strategy demonstrates higher crystallinity and smaller phase separation morphology, resulting in an outstanding PCE of 16.58% with low energy loss and high fill factor, which is higher than the CF‐based device (15.08%). Finally, the 1.00 cm2 device exhibits a high PCE of 14.82%, which is one of the highest values for OSCs prepared by blade‐coating based on TL solvent. This specific strategy combines blade‐coating with nonhalogenated solvent processing shows outstanding synergy in optimization of morphology, demonstrating excellent potential for the preparation of highly efficient large area OSCs. [ABSTRACT FROM AUTHOR]

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This work continues the study on the doping of chemically deposited PbS(I) layers and discusses the effect of cobalt ions on their morphology and the structural, optical, and photoelectric properties. It is shown using energy-dispersive elemental analysis that cobalt is found in the films at a cobalt-chloride concentration of ≥ 0.04 mol/l in the reaction mixture. The synthesized PbS(I,Co) films retain the B1 cubic structure (sp. gr. ). A tendency to an increase in the band gap of the PbS(I,Co) films from 0.57 to 0.75 eV with an increase in the nanoparticle content in them from 1 to ~8% during 1.5-h deposition and from 0.57 to 0.68 eV with an increase in the nanoparticle content from 13 to ~28% during 3-h deposition is observed. The concentration dependence of the voltage sensitivity of the PbS(I,Co) films deposited for 1.5 h contains two maxima corresponding to nanoparticle contents of 1 and 4%. During 3-h synthesis, a sharp decrease in the photoresponse with an increase in the nanoparticle content to 13‒28% in the PbS(I,Co) layers is found. It is shown that the photocurrent density decreases with increasing content of nanoparticles in films in the series PbS(Co) → PbS → PbS(I,Co) → PbS(I). [ABSTRACT FROM AUTHOR]

Ternary strategy has been demonstrated to be an effective way to improve power conversion efficiency (PCE) of single‐junction organic solar cells (OSCs). Herein, high‐efficiency ternary OSCs are fabricated based on the PBDB‐T:DO‐2F binary system and acceptor IDTT‐OB with asymmetric side chains as the third component. The introduction of nonfullerene acceptors (NFAs) IDTT‐OB as a third component can efficiently increase the compatibility of the ternary system, reduce the crystallinity of DO‐2F, optimize the blend film morphology, improve the charge transport and collection, suppress the bimolecular recombination, and reduce the nonradiative energy loss (ΔEnonrad). Finally, the PBDB‐T:DO‐2F:IDTT‐OB‐based ternary device exhibits a high PCE of 14.09% with Voc of 0.87 V, Jsc of 21.47 mA cm−2, and fill factor of 75.70%, which is about 30% higher than the corresponding PBDB‐T:DO‐2F‐ and PBDB‐T:IDTT‐OB‐based binary devices. Meanwhile, the ternary device also achieves a very low ΔEnonrad of 0.22 eV. This work indicates that the ternary strategy can effectively optimize morphology of active layer, reduce nonradiative energy loss, and further improve photovoltaic performance of OSCs. [ABSTRACT FROM AUTHOR]

Volatile solid additives have emerged as a promising strategy for enhancing film morphology and promoting the power conversion efficiency (PCE) of organic solar cells (OSCs). Herein, a series of novel polycyclic aromatic additives with analogous chemical structures, including fluorene (FL), dibenzothiophene (DBT), and dibenzofuran (DBF) derived from crude oils, are presented and incorporated into OSCs. All these additives exhibit strong interactions with the electron-deficient terminal groups of L8-BO within the bulk-heterojunction OSCs. Moreover, they demonstrate significant sublimation during thermal annealing, leading to increase free volumes for the rearrangement and recrystallization of L8-BO. This phenomenon leads to an improved film morphology and an elevated glass-transition temperature of the photoactive layers. Consequently, the PCE of the PM6:L8-BO blend has been boosted from 16.60% to 18.60% with 40 wt% DBF additives, with a champion PCE of 19.11% achieved for ternary PM6:L8-BO:BTP-eC9 OSCs. Furthermore, the prolonged shelf and thermal stability have been observed in OSCs with these additives. This study emphasizes the synergic effect of volatile solid additives on the performance and thermal stability of OSCs, highlighting their potential for advancing the field of photovoltaics., (© 2024 Wiley‐VCH GmbH.)

Incorporating a third component into binary organic solar cells (b-OSCs) has provided a potential platform to boost power conversion efficiency (PCEs). However, gaining control over the non-equilibrium blend morphology via the molecular design of the perylene diimide (PDI)-based third component toward efficient ternary organic solar cells (t-OSCs) still remains challenging. Herein, two novel PDI derivatives are developed with tailored molecular planarity, namely ufBTz-2PDI and fBTz-2PDI, as the third component for t-OSCs. Notably, after performing a cyclization reaction, the twisted ufBTz-2PDI with an amorphous character transferred to the highly planar fBTz-2PDI followed by a semi-crystalline character. When incorporating the semi-crystalline fBTz-2PDI into the D18:L8-BO system, the resultant t-OSC achieved an impressive PCE of 18.56%, surpassing the 17.88% attained in b-OSCs. In comparison, the addition of amorphous ufBTz-2PDI into the binary system facilitates additional charge trap sites and results in a deteriorative PCE of 14.37%. Additionally, The third component fBTz-2PDI possesses a good generality in optimizing the PCEs of several b-OSCs systems are demonstrated. The results not only provided a novel A-DA'D-A motif for further designing efficient third component but also demonstrated the crucial role of modulated crystallinity of the PDI-based third component in optimizing PCEs of t-OSCs., (© 2024 Wiley‐VCH GmbH.)

In organic photovoltaic cells, the solution-aggregation effect (SAE) is long considered a critical factor in achieving high power-conversion efficiencies for polymer donor (PD)/non-fullerene acceptor (NFA) blend systems. However, the underlying mechanism has yet to be fully understood. Herein, based on an extensive study of blends consisting of the representative 2D-benzodithiophene-based PDs and acceptor-donor-acceptor-type NFAs, it is demonstrated that SAE shows a strong correlation with the aggregation kinetics during solidification, and the aggregation competition between PD and NFA determines the phase separation of blend film and thus the photovoltaic performance. PDs with strong SAEs enable earlier aggregation evolutions than NFAs, resulting in well-known polymer-templated fibrillar network structures and superior PCEs. With the weakening of PDs' aggregation effects, NFAs, showing stronger tendencies to aggregate, tend to form oversized domains, leading to significantly reduced external quantum efficiencies and fill factors. These trends reveal the importance of matching SAE between PD and NFA. The aggregation abilities of various materials are further evaluated and the aggregation ability/photovoltaic parameter diagrams of 64 PD/NFA combinations are provided. This work proposes a guiding criteria and facile approach to match efficient PD/NFA systems., (© 2024 Wiley‐VCH GmbH.)

This work presents a facile sol–gel method for the deposition of ZnO and ZnO:Mg films. The films are spin coated on silicon and quartz substrates. The impact of magnesium concentrations (0, 0.5, 1, 2 and 3 wt%) and post-annealing treatments (300–600 °C) on the film’s structural, vibrational and optical properties is investigated. Undoped ZnO films crystallize in the wurtzite phase, with crystallite sizes ranging from 9.1 nm (300 °C) to 29.7 nm (600 °C). Mg doping deteriorates the film crystallization and shifting of 002 peak towards higher diffraction angles is observed, indicating the successful incorporation of Mg into the ZnO matrix. ZnO:Mg films (2 wt%) possess the smallest crystallite size, ranging from 6.2 nm (300 °C) to 25.2 nm (600 °C). The highest Mg concentration (3 wt%) results into a segregation of the MgO phase. Lattice constants, texture coefficients and Zn–O bond lengths are discussed. The diminution of the c lattice parameter is related to the replacement of Zn2+ by Mg2+ in the ZnO host lattice. The vibrational properties are studied by Fourier transform infrared (FTIR) spectroscopy. IR lines related to Mg–O bonds are found for ZnO:Mg films with dopant concentrations of 2 and 3 wt%. The optical characterization showed that the transmittance of ZnO:Mg thin films increased from 74.5% (undoped ZnO) to about 89.1% and the optical band gap energy from 3.24 to 3.56 eV. Mg doping leads to a higher refractive index compared to undoped ZnO films. The FESEM (field emission scanning electron microscopy) technique is used for observation of the surface morphology modification of ZnO:Mg films. The doped ZnO films possess a smoother grained surface structure, opposite to the wrinkle-type morphology of undoped sol–gel ZnO films. The smoother surface leads to improved transparency of ZnO:Mg films.

The advent of small molecule non-fullerene acceptor (NFA) materials for organic photovoltaic (OPV) devices has led to a series of breakthroughs in performance and device lifetime. The most efficient OPV devices have a combination of electron donor and acceptor materials that constitute the light absorbing layer in a bulk heterojunction (BHJ) structure. For many BHJ-based devices reported to date, the weight ratio of donor to acceptor is near equal. However, the morphology of such films can be difficult to reproduce and manufacture at scale. There would be an advantage in developing a light harvesting layer for efficient OPV devices that contains only a small amount of either the donor or acceptor. In this work we explore low donor content OPV devices composed of the polymeric donor PM6 blended with high performance NFA materials, Y6 or ITIC-4F . We found that even when the donor:acceptor weight ratio was only 1:10, the OPV devices still have good photoconversion efficiencies of around 6% and 5% for Y6 and ITIC-4F , respectively. It was found that neither charge mobility nor recombination rates had a strong effect on the efficiency of the devices. Rather, the overall efficiency was strongly related to the film absorption coefficient and maintaining adequate interfacial surface area between donor and acceptor molecules/phases for efficient exciton dissociation.

For this study, functional precoalescence (internally crosslinked) and postcoalescence (crosslinkable) conventional latexes were made using seeded semi-continuous emulsion polymerization. Nanosize polymer latexes with or without crosslinkable functional groups were made using a modified microemulsion copolymerization process. Films cast from conventional and nanosize latex were characterized using specific end use tests and fundamental properties using dynamic mechanical analysis, modulated differential scanning calorimetry, and atomic force microscopy. This study compares conventional and nanosize latex with respect to the effect of the type and level of crosslinking, particle size and distribution on latex film formation and morphology, and end use and fundamental properties. Nanosize latex films in general have superior gloss, solvent resistance, and adhesion but inferior water resistance. Stress–strain Young's modulus showed an increase as a function of increasing crosslinker level in the nanosize latex films. [ABSTRACT FROM AUTHOR]

The development of high‐performance polymer acceptors is the key challenge for all‐polymer solar cells (All‐PSCs), especially related morphology control in the blend film. Herein, we introduce a thiophene with oligoethylene oxide side chain (TOE) as the third unit into a D‐A copolymer PYT by simple random polymerization. Rigid‐fused unit Y5 with large planar or quasi‐plane surfaces are partially substituted to obtain a series of novel random terpolymers PYT‐TOE(x) (x represents the molar ratio of TOE unit). The electron‐deficient unit Y5 partly replaced by electron‐rich unit TOE realizes the increase of LUMO energy levels. More importantly, a moderate amount loading of TOE not only modulate the polymer acceptor solubility and molecule arrangement, but also perfect the compatibility between the polymer donor and acceptor. Thus, optimized crystallinity and π‐π stacking of blend film are obtained, which is favorable for charge transfer and better film morphology. Eventually, accompanied by improved JSC, VOC and FF simultaneously, the device photoelectric conversion efficiency (PCE) increase from 11.75 % for PBDB‐T:PYT to 12.77 % for PBDB‐T:PYT‐TOE(10). These results indicate that the random ternary copolymerization of small molecule acceptor with functional third unit TOE is a simple but effective strategy to develop polymer acceptors for high‐efficiency All‐PSCs. [ABSTRACT FROM AUTHOR]

Herein, we design and characterize 9-heterocyclic ring non-fullerene acceptors (NFAs) with the extended backbone of indacenodithiophene by cyclopenta [2,1-b:3,4-b’] dithiophene (CPDT). The planar conjugated CPDT donor enhances absorption by reducing vibronic transition and charge transport. Developed NFAs with different end groups shows maximum absorption at approximately 790–850 nm in film. Because of the electronegative nature of the end-group, the corresponding acceptors showed deeper LUMO energy levels and red-shifted ultraviolet absorption. We investigate the crystallinity, film morphology, surface energy, and electronic as well as photovoltaic performance. The organic photovoltaic cells using novel NFAs with the halogen end groups fluorine or chlorine demonstrate better charge collection and faster exciton dissociation than photovoltaic cells using NFAs with methyl or lacking a substituent. Photovoltaic devices constructed from m-Me-ITIC with various end groups deliver power conversion efficiencies of 3.6–11.8%.

Organic–inorganic halide perovskite (OIHP) solar cells have garnered great attention in the last decade since they continuously approach the Shockley–Queisser Limit. Compared with conventional organic and inorganic semiconductors, OIHPs possess the high tolerance on defects due to the dominated intrinsically shallow‐level carrier‐trapping centers. However, the existence of defects still causes the ion migration, produces the hysteresis effect, and accelerates the film degradation, eventually suppressing the device efficiency and stability. In this Review Article, we summarize recent impressive advance on passivating OIHP defects and discuss the future horizon of exploiting high‐efficiency and long‐stability OIHP solar cells in terms of defect managements. [ABSTRACT FROM AUTHOR]

Owing to the advantages of low synthetic cost and high scalability of synthesis, polythiophene and its derivatives (PTs) have been of interest in the community of organic photovoltaics (OPVs). Nevertheless, the typical efficiency of PT based photovoltaic devices reported so far is much lower than those of the prevailing push-pull type conjugated polymer donors. Recent studies have underscored that the excessively low miscibility between PT and nonfullerene acceptor is the major reason accounting for the unfavorable active layer morphology and the inferior performance of OPVs based on a well-known PT, namely PDCBT-Cl and a non-halogenated nonfullerene acceptor IDIC. How to manipulate the miscibility between PT and acceptor molecule is important for further improving the device efficiency of this class of potentially low-cost blend systems. In this study, we introduced different numbers of F atoms to the end groups of IDIC to tune the intermolecular interaction of the hypo-miscible blend system (PDCBT-Cl:IDIC). Based on calorimetric, microscopic, and scattering characterizations, a clear relationship between the number of F atoms, miscibility, and device performance was established. With the increased number of F atoms in IDIC, the resulting acceptors exhibited enhanced miscibility with PDCBT-Cl, and the domain sizes of the blend films were reduced substantially. As a result, distinctively different photovoltaic performances were achieved for these blend systems. This study demonstrates that varying the number of F atoms in the acceptors is a feasible way to manipulate the molecular interaction and the film morphology toward high-performance polythiophene:nonfullerene based OPVs.

Ternary organic photovoltaic (OPV) strategy is an effective but facile approach to enhance the photovoltaic performance for single-junction devices. Herein, a series of ternary OPVs were fabricated by employing a wide bandgap donor (PBDB-TF) and two acceptor-donor-acceptor (A-D-A)-type nonfullerene small molecule acceptors (NF-SMAs, called F-2Cl and 3TT-OCIC). As the third component, the near-infrared SMA, 3TT-OCIC, has complementary absorption spectrum, narrow bandgap and well-compatible crystallization property to the host acceptor (F-2Cl) for efficient ternary OPVs. With these, the optimal ternary devices yield significantly enhanced power conversion efficiency of 15.23%, one of the very few examples with PCE higher than 15% other than Y6 systems. This is mainly attributed to the increased short-circuit current density of 24.92 mA cm−2 and dramatically decreased energy loss of 0.53 eV. This work presents a successful example for simultaneously improving current, minimizing energy loss and together with modifying the morphology of active layers in OPVs, which will contribute to the further construction of high performance ternary OPVs. [ABSTRACT FROM AUTHOR]

Ternary solar cells comprising both fullerene and nonfullerene acceptors have shown a rapid increase in power conversion efficiency, which holds promise in commercial applications. Despite the rapid progress, there is still a lack of fundamental understanding of the relations between microstructure and (photovoltaic/mechanical) properties in these ternary blend systems. In this work, the dependence of molecular packing, phase separation, mechanical properties, and photovoltaic performance on acceptor composition of a recently certificated ternary system is thoroughly investigated by combined scattering and microscopy characterizations. It is demonstrated that incorporating a small amount (20% by weight) PC71BM to the PM6:N3 binary blend can afford the best device efficiency and the highest ductility simultaneously. This maximum performance is due to the optimized molecular order, orientational texture, and phase separation. Additionally, increasing the amount of PC71BM results in higher elastic modulus, as probed by two distinct methods. A more crucial observation is that the elastic modulus of ternary blends can be well captured by an extended Halpin–Tsai model. This finding is expected to enable the prediction of the elastic modulus of various kinds of ternary blends that are widely used in solar cells and other electronics. [ABSTRACT FROM AUTHOR]

Summary: The relevance of graphene‐based materials throughout the niche area of perovskite solar cells (PSCs) is indeed the main focus of this review. Specific properties of two types of solar cell materials, namely hybrid perovskites and graphene‐based materials are at the core of significant breakthroughs in a wide range of applications. The specific features of graphene‐based materials, along with their unique properties, have been utilized mainly in the development of photovoltaic devices. PSCs are known to have promising device performance and surpass other third‐generation solar cells, including organic photovoltaics, quantum dot solar cells, and dye‐sensitized solar cells. However, PSCs address several limitations in the device mechanism and material stability. PSCs performance tends to deplete over time due to several factors such as the degradation of materials used in the device caused by exposure of thermal and moisture, as well as an undesired chemical reaction in the interfaces. Several experimental studies, especially on the integration of carbon materials, including the graphene, have been extensively explored. The integration of graphene‐based materials is one of the potential methods for altering and modifying components in PSCs, including perovskite structure and charges transport layers. Therefore, this review gives an overview of recent progress in the development of PSCs with the integration of graphene‐based materials. The emphasis will be on the influence brought by graphene‐based materials on the charge transport mechanism at the interfaces and perovskite morphology toward the improvement of photovoltaic performance and stability. [ABSTRACT FROM AUTHOR]

Solution processing of crosslinkable small molecular thin films is potentially attractive for the fabrication of large-area display panels based on organic light-emitting diodes (OLEDs). The characteristics of a wet-processed film made of a thermally crosslinked small-molecular material can be controlled by simply adding a cosolvent to its solution. The surface morphology of a nanometer-scale thin film made of N4,N4′-di(naphthalen-1-yl)-N4,N4′-bis(4-vinylphenyl)biphenyl-4,4′-diamine (VNPB), dissolved in chlorobenzene, improved dramatically after the addition of 20% cyclohexanone. At the same time, better resistance of the crosslinked layer to a number of solvents frequently used in the fabrication of the adjacent emitting layer was achieved. Moreover, the maximum current efficiency in the binary solvent device increased significantly to 22.2 Cd/A, compared to 9.7 Cd/A in the reference device without VNPB, and the device lifetime was extended by up to 74.8%. This illustrates a simple and additive-free strategy to prevent the formation of defects in solution processed thin-film stacks made of small-molecular materials. The insights gained will be helpful in the solution-based manufacture of large-area OLEDs and other optoelectronic components. [ABSTRACT FROM AUTHOR]

Polycrystalline films of PbS:Fe are obtained via hydrochemical deposition from an ammonia-citrate bath containing 10−5 to 7 × 10−3 M of FeCl2 doping additive. The films' morphology is studied along with their structural and optical properties. An increase in the lattice parameter of PbS doped up to 5 × 10‒3 M testifies to the interstitial position of Fe2+ ions, while a subsequent reduction in the lattice parameter is due to some of the lead ions in the PbS crystal lattice being replaced with iron ions of a smaller radius. Doping with iron ions produces impurity absorption bands in the optical absorption spectra of PbS:Fe films. Rearrangement of the zone structure of lead sulfide near the edge of the band gap is observed in a film obtained from a solution containing 5 × 10−3 M FeCl2. The change in the zone structure is due to the lead ions in the PbS lattice being replaced with iron ions. [ABSTRACT FROM AUTHOR]