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Introducing additives into perovskite layers is an effective method to enhance the power conversion efficiency (PCE) and operation stability of perovskite solar cells (PSCs). Herein, we reported an addition of carbon nanodots (CNDs) into the CsPbI2Br photoactive layer to boost performance of the related PSCs. It is found that the trap density can be notably suppressed, and the crystallinity can be enhanced after introducing CNDs with an optimal quantity. The PSC with 1.0 wt% addition of CNDs delivers a notable improved average PCE of 13.77% (the highest PCE: 14.69%) from that of 12.14% for the control device without CND addition. Moreover, the CND-added CsPbI2Br PSCs exhibit superior stability, i.e., ∼86 % retention of the initial PCE after 160 h aging in air with the humidity of 20%–30%, to the control device.

Perovskite and organic solar cells usually require electron-transport interlayers to efficiently transport electrons from the photoactive layer to the metal electrode. In general, pure organic or i...

To make quantum dot sensitized solar cells (QDSCs) competitive, a power conversion efficiency (PCE) comparable to other developing solar cells is required. Significant attention has been paid to undoped or nitrogen (N) doped carbon quantum dots (N-CQDs) for use as sensitizers or light harvesters in solar cells. However, to our knowledge, the nitrogen and sulfur (S) co-doped CQDs (N, S-CQDs) have never been used as the absorbing layer alone. In the present work, we synthesize nitrogen and sulfur co-doped carbon quantum dots (N, S-CQDs) from a single precursor thioacetamide (TA), via a hydrothermal method. The as-prepared N, S-CQDs were employed as a “green” photoactive layer in TiO2 film, as photoanode. The solar cell delivered an open-circuit voltage (Voc) of 0.43 V, short-circuit current (Jsc) of 0.61 mA/cm−2, fill factor (FF) of 52 %, and PCE of 1.36%; highest among all the carbon-based QDSCs. Moreover, Device-NS showed more stability over 48 h compared to Device-C and Device-N. Undeniably, the achieved PCE is not satisfactory; however, the upgraded device fabrication and structural design may improve PCE and current densities while sustaining the high open-circuit voltage. This study demonstrated the potential application of N, S-CQDs for low-cost, “green” quantum dot solar cell applications.

Although the power conversion efficiency (PCE) of perovskite solar cells (PSCs) has improved greatly in recent years, the challenges of efficiency and stability still need to be overcome before these solar cells can be used in commercial applications. Here, a weak acid buffer, hydroxyethyl piperazine ethane sulfonic acid (HEPES), is used to passivate the interface of an SnO2 electron transport layer (ETL) and a photoactive layer in n-i-p solar cells. The device efficiency based on a SnO2/HEPES ETL reaches 20.22%, which is 9.7% higher than that of the control (18.43%), and the device stability is also significantly improved. The improvement in the device performance is mainly due to the introduction of the HEPES interface layer to adjust the interface energy level, which also improves the crystallinity of the perovskite film and reduces the interface defects. Electrochemical impedance spectroscopy and transient photovoltage/photocurrent results show that the HEPES-modified PSCs have lower charge transfer resistance, weaker leakage current intensity and improved interfacial charge separation and transport.

Herein, two simple furan-based polymers PFO3 and PFO4 grafting oligoethylene glycol (OEG) side chains are developed. PFO3 and PFO4 feature high hole mobility, large dielectric constant and good solubility. Compared to PFO4, PFO3 with shorter side chains demonstrates larger absorption coefficient and deeper electronic energy level. The air- and ethanol/water-processed OSCs based on PFO4:fullerene derivative (PCBO-12) show a modest efficiency of 2.06%. However, PFO3:PCBO-12 OSCs yield a higher efficiency of 3.03% due to the simultaneously enhanced photovoltaic parameters. PFO3- and PFO4-based devices remain 64.5% and 51.2% of their initial efficiency after continuous illumination for 200 h in inert atmosphere, respectively. Surprisingly, the remained efficiency ratio is increased to 81.6% and 69.1% for PFO3- and PFO4-based devices suffering from discontinuous illumination yet with the same soaking time of 200 h in inert atmosphere. However, the above phenomenon is not observed for other three photovoltaic systems without abundant OEG groups when adopting discontinuous illumination. The infrared spectroscopy and X-ray photoelectron spectroscopy unravel that the repaired efficiency of PFO3- or PFO4-based devices should be resulted from the self-healing of hydrogen bonds in photoactive layer. Our work will provide guidance for the future design of donor polymers for eco-friendly OSCs featuring high stability.

Flexible photodetectors have attracted much attention due to their great potentials in wearable electronics, bendable image sensors, and environmental monitoring, which requires functional components with good machinal properties. Herein, we introduced a novel metallic two-dimensional (2D) material, MXene, to form the electrodes by a spray-coating method and zero-dimensional (0D) PbS quantum dots (QDs) to work as photoactive layer. All solution-processable fabrication technique contributes to a simplified, low-cost and large-scale route to develop flexible photodetectors. Benefiting from the excellent conductivity of MXene electrodes and broadband photoresponse of PbS QDs, our devices realize a high detectivity up to 2.4×1011 Jones and exhibit good stability even after 1000 bending cycles. This work provides a new device configuration with 2D electrodes and 0D photoactive layers for designing high-performance flexible electronics.

In this study, an efficient strategy is used to prepare perovskite photoactive layer with superb optoelectronic merits by utilizing polyaniline polymer as an efficient additive to improve perovskite quality. As a result, we prove that the small content of polyaniline (PANI) provides not only suppresses the perovskite defects and lead iodide but also produces a passivation impact. By regarding using macromolecular phases with long chain polymers, the generation of a PANI-perovskite cross-linking is possible. The cross-linking acts to bridge the perovskite crystals, mitigating carrier trapping by grain boundaries and achieving remarkable air stability against humid, which has not been obtainable with tiny molecules defect passivating materials. Also, PANI promoted the development of Lewis base adduct with the perovskite precursor, which, maximized the activation energy for nucleation and growth of the perovskite phase. Therefore, the perovskite layer with optimized PANI additive showed higher crystallinity in (110) crystal plane. After PANI addition, the perovskite grains found to be enlarged from 350 nm to 620 nm. Also, the PSCs with PANI showed suppressed luminescence effect, which indicates lower recombination rates. The SCLC measurements revealed that the PANI additive improving the interfacial contact between the ZnO and perovskite due to reduction the trapped density from 1.78 × 1016 cm-3 to 2.46 × 1015. Consequently, the champion cell yields an efficiency of 17.39% for 4% polyaniline doped electron transport material with negligible hysteresis. This reduces PSC instability generating a device that retained 93% of its original performance after 600 h maintaining in air conditions without any encapsulation.

Since the most high-performing donor polymers in polymer solar cells (PSCs) possessed the deep highest occupied molecular orbital (HOMO) level, interfacial engineering on anode contact is becoming increasingly important. Herein, we demonstrated efficient PSCs using an anionic poly(styrene sulfonate) (PSS) as an anode interfacial layer (AIL). With the formation of the dipole layer, the effective work function (WF) of indium tin oxide (ITO) electrode is significantly increased from 4.8 to 5.3 eV, providing favorable energetic alignment to the quasi-Fermi level of various donor polymers. Moreover, by incorporating cationic polyelectrolytes as a cathode interfacial layer, a pair of electric dipole layers induces a strong built-in electric field across the photoactive layer to drive efficient sweep-out of photogenerated charges. Consequently, the device with PSS AIL exhibited high power conversion efficiencies of 9.2 and 14.8% in PTB7-Th:PC71BM- and PM6:Y6-based PSCs, respectively, both of which are higher than those of the devices with PEDOT:PSS.

Recent studies have shown that the addition of inorganic metal oxide nanoparticles (NPs) can enhance the power conversion efficiency (PCE) of organic solar cells (OSCs). In this paper influences of mixing ZnO (n-type) and NiO (p-type) NPs to the photoactive layer of poly(3-hexylthiophene) and [6,6]-phenyl C61-butyric acid methyl ester (P3HT:PC61BM) were discussed. It is interesting to note that the optimized device with ZnO:NiO NPs achieved a PCE of 4.37% compared to the bare-doped NPs cell (3.56%) under light illumination intensity of 100 mW/cm2. Further investigations based on charge extraction by linearly increasing voltage (CELIV) technique have been carried out to explain the possible reason for PCE enhancement. The improved performance is attributed to the enhanced charge carrier’s transportation and reduced exciton (electron/hole pair) annihilation. As evidence by CELIV measurements, the PCE degrades with further addition of ZnO:NiO NPs concentration to the photoactive layer due to deep-trap states.

ConspectusOrganic photovoltaics (OPVs) with a photoactive layer containing a blend of organic donor and acceptor species are considered to be a promising technology for clean energy owing to their unique flexible form factor and good solution processability that can potentially address the scalability challenges. The delicate designs of both donors and acceptors have significantly enhanced the power conversion efficiency of OPVs to more than 18%. Nonfullerene small-molecule acceptors (NFAs) have played a critical role in enhancing the short-circuit current density (JSC) by efficiently harvesting near-infrared (NIR) sunlight. To take full advantage of the abundant NIR photons, the optical band gap of NFAs should be further reduced to improve the performance of OPVs. Incorporating highly polarizable selenium atoms onto the backbone of organic conjugated materials has been proven to be an effective way to decrease their optical band gap. For example, a selenium-substituted NFA recently developed by our group has attained a JSC of approximate 27.5 mA cm-2 in OPV devices, surpassing those of most emerging photovoltaic systems. Inspired by this advance, we concentrate on the topic of selenium-containing materials in this Account to incite readers' interest in further exploring this series of materials.In this Account, we first compare the differences among chalcogen heterocycles and discuss the influence of fundamental electronic behavior on the collective photoelectrical properties of the resulting materials. The superior features of selenium-substituted materials are summarized as follows: (1) The large covalent radius of selenium can diminish the π-orbital overlap, rendering enhanced quinoidal resonance character and a narrowed optical band gap of resulting materials. (2) The selenium atom is more polarizable than sulfur owing to its larger and looser outermost electron cloud, enabling enhanced intermolecular Se-Se interaction and increased charge carrier mobility of relevant materials in the solid state. We then focus on summarizing the design rules for various categories of selenium-containing materials including polymer donors, small-molecule acceptors, and polymer acceptors, especially those composed of ladder-type polycyclic units. The motivation for incorporating selenium atoms into these materials and the structure-property relationships were thoroughly elucidated. Specifically, we discuss the changes in the optical band gap, charge carrier mobility, and molecular packing induced by selenium substitution and correlate the effects of these changes with the exciton behaviors, energy loss, and nanoscale film morphology of corresponding OPV devices. Furthermore, we point out the intrinsic stability of selenium-containing materials under maximum-power-point tracking and long-term photo- or thermostress and indicate their potential use in semitransparent and tandem solar cells. At the end, the prospect of future research focuses and the possible applications of selenium-containing materials in the OPV field are discussed.

High-quality nitrogen-doped carbon quantum dots (NCQDs) are synthesized using domestic microwave-assisted pyrolysis method. These show excellent physiochemical and optical properties such as wide spectral adsorption, high charge carrier extraction, fast charge carrier transportation, and tuneable emission. These NCQDs are introduced in the dye sensitized solar cell (DSSC)/quantum dot sensitized solar cell (QDSSC) structure to improve the performance. The effect of synthesized NCQD as sensitizer, co-sensitizer, and co-photoactive layers is investigated for the DSSC/QDSSC structure. High photoconversion efficiency of 8.75% and photocurrent density of 18.13 mA/cm2 is achieved under one sun irradiation when NCQDs are used as co-photoactive layer. The obtained power conversion efficiency is approximately 55% and 99% better than NCQDs as co-sensitizer and sensitizer, respectively. The incorporation of the NCQDs in the photoactive layer synergically enhanced photo absorbance and reduced recombination between photoanode and electrolyte. A large number of anchoring sites for dye, highly conducting photoanode, fast charge carrier transportation, and inherent light-emitting photo-fluorescent property of NCQDs in mesoporous titania are understood to be responsible for this enhancement. The optimized weight ratio of citric acid and urea in the synthesis of NCQDs has provided the widened light response, low recombination rate, and high charge transport in the DSSC structure.

The Nickel-Graphene core-shell nanoparticles (Ni-GR CSNPs) were synthesized by thermal chemical vapor deposition (T-CVD) method. The prepared materials were characterized by different physicochemical techniques. The sizes of the Ni−GR NPs are in the range of approximately 60–200 nm as measured from the outermost graphene layer. The Ni-GR CSNPs were incorporated to the device’s photoactive layer, which supporting electron transfer faster by the charge selective graphene and the extraction of electrons prevented the recombination of holes and electrons. The surface roughness of photoactive layer was controlled by inserting a thin layer of ZnO with different thickness between the photoactive layer and the back contact. Finally, the device with the structure of glass/indium tin oxide (ITO)/(polyethylene dioxy thiophene doped with polystyrene-sulfonic acid (PEDOT:PSS)/SnS + PTB7 + Ni-GR CSNPs/zinc oxide (ZnO)/E-GaIn showed a power conversion efficiency (PCE) of ~ 3.2%.

Small-area perovskite photodiodes with an active area of $50\,\,\mu \text{m}\,\,\times 50\,\,\mu \text{m}$ are achieved, showing both high specific detectivity and excellent stability. The device exhibits a low dark current density of $\sim 1.6\times 10 ^{-8}$ A/cm2 at a reverse bias of 0.1 V, a peak photoresponsivity of 1.74 A/W, and a peak specific detectivity of $1.5\times 10 ^{13}$ Jones. Moreover, the device also shows superior photoresponse and thermal stability after continuous 1000 cycles of light switching and 400 h of thermal aging at 85 °C. The high performance is ascribed to the blocking of minority carrier injection from electrodes under a reverse bias and the high crystal quality and thermal stability of the CH3NH3(MA)-free perovskite photoactive layer.

This paper presents recent progress in computational modeling on blend morphology of silicon nanowires (SiNWs) dispersed in a conjugated polymer poly(3-hexylthiophene) P3HT hybrid solar cells. Mixtures of poly-(3-hexyl-thiophene) as electron-donor and silicon nanowires as electron-acceptor materials have been widely investigated. In this work, we extracted five parameters such as the ideality factor, the saturation current, the photocurrent, the series and the shunt resistances from measured current–voltage characteristics. These parameters are used in the simulation study to obtain the theoretical curves by using the Newton-Raphson method developed in MATLAB code. A good agreement is obtained between theoretical model and experimental measurement of electrical characteristics. Taking the advantage of the simulation study, we determined the solar cell parameters to study the effect of SiNWs concentration, the type of solvent used for film fabrication and the thickness of photoactive layer in the performance of ITO/PEDOT:PSS/P3HT:SiNWs/Al hybrid solar cells in target to achieve the optimal condition: 15% of SiNWs dispersed within P3HT matrix fabricated from THF solution and 115 nm thickness photoactive layer with fill factor FF and efficiency η equal to 48% and 0.08%, respectively.

In this study, an effective and simple approach for optimizing the performance of both cathode and anode interlayers in OSCs is demonstrated using 4-heptyl-4'-cyanobiphenyl (7CB) to dope a classic cathode (ZnO and SnO2) or an anode interlayer [poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)]. Because of the enhanced light absorption, improved physical contact between a photoactive layer and an interlayer, and increased carrier recombination, all of the devices based on a 7CB-doped interlayer show increased short-circuit current density (Jsc), fill factor (FF), and power conversion efficiency (PCE) compared to the corresponding undoped interlayer, regardless it is the anode interlayer or the cathode interlayer, which is a rare phenomenon in the interlayer modification field.

The photoelectric and optical characteristics of an organic solar cell (OSС) with a hole-transport layer based on a polyaniline complex and a photoactive layer with a bulk heterojunction based on P3HT polythiophene derivative and PC71BM fullerene have been studied. The results of modeling the optical properties of the functional layers and experimental measurements of the OSC characteristics enabled the optimal values of the thickness of the functional layers resulting in the maximum power conversion efficiency of the device to be identified. It has been determined that the hole-transport layer with a thickness of 30–60 nm, while having a transmission of more than 80%, effectively transferred holes to the photoanode from the photoactive layer, in which the exciton generation rate was 5.6–5.9 × 1016 cm–2 s–1. These values of the exciton generation rate at the maximum total light absorption in the device were provided by a photoactive layer with a thickness of 90–100 nm.

Recently, the bulk heterojunction (BHJ)-based photoactive layer has been favored over the planar heterojunction (PHJ)-based photoactive layer for organic photovoltaics (OPVs), owing to the evitable thickness limit of the latter induced by the low mobility of charge carriers. However, under dim indoor light conditions, the PV performance becomes immune to the resistive components of the PHJ OPVs, such as a thick photoactive layer, thereby rendering them attractive for operating indoors. In this study, we devise and demonstrate indoor OPVs with a PHJ-based photoactive layer constituting poly(3-hexylthiophene-2,5-diyl) (P3HT) and indene-C60 bisadduct (ICBA). The performance of the PHJ OPVs was optimized by modulating the thickness of the ICBA layer under a 1000 lx light-emitting diode lamp. OPVs with a 65 nm-thick ICBA layer exhibited excellent indoor performance with a power conversion efficiency of 15.3 ± 0.3%, comparable to that of the reference BHJ OPVs (15.0 ± 0.2%). No noticeable performance degradation was observed by increasing the thickness of the PHJ-based photoactive layer; instead, a thick photoactive layer only enhanced the light absorption, resulting in excellent indoor performance with a higher photocurrent.

The third component played an increasingly significant role in polymer solar cells (PSCs), especially for the morphological impact. Here, we use a ternary polymer donor (TBFCl50-BDD) and organic small molecule acceptor (BTP-4F) as the main material and introduce a third component (PC71BM) to enhance the morphology of the photoactive layer and result in improved device performance. The TBFCl50-BDD:BTP-4F based PSCs only exhibited an efficiency of 10.58%, while The power conversion efficiency of ternary device (TBFCl50-BDD:BTP-4F:PC71BM) reached 13.15%. Importantly, the introduction of PC71BM can not only improve the morphology of the active layer and promote more efficient exciton transport, but also influence the molecular arrangement for better crystallization performance. This work offers an effective method for optimization of the morphology to enhance the properties of PSCs.

In perovskite solar cells, doped organic semiconductors are often used as charge-extraction interlayers situated between the photoactive layer and the electrodes. The π-conjugated small molecule 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9-spirobifluorene (spiro-OMeTAD) is the most frequently used semiconductor in the hole-conducting layer1-6, and its electrical properties considerably affect the charge collection efficiencies of the solar cell7. To enhance the electrical conductivity of spiro-OMeTAD, lithium bis(trifluoromethane)sulfonimide (LiTFSI) is typically used in a doping process, which is conventionally initiated by exposing spiro-OMeTAD:LiTFSI blend films to air and light for several hours. This process, in which oxygen acts as the p-type dopant8-11, is time-intensive and largely depends on ambient conditions, and thus hinders the commercialization of perovskite solar cells. Here we report a fast and reproducible doping method that involves bubbling a spiro-OMeTAD:LiTFSI solution with CO2 under ultraviolet light. CO2 obtains electrons from photoexcited spiro-OMeTAD, rapidly promoting its p-type doping and resulting in the precipitation of carbonates. The CO2-treated interlayer exhibits approximately 100 times higher conductivity than a pristine film while realizing stable, high-efficiency perovskite solar cells without any post-treatments. We also show that this method can be used to dope π-conjugated polymers.

Copper(І) iodide (CuI) is a very efficient inorganic p-type material and has a potential application in polymer solar cells (PSCs). However, the solution-processed CuI film tends to be rough surface morphology. Herein, CuI nanoparticles (NPs) were synthesized by water decomposing the CuI N,N-dimethylformamide (DMF) dispersion and used as hole transporting layers (HTLs) of PSCs with the configuration of ITO/CuI/P3HT:PC61BM/Ca/Al. As a result, a smooth and uniform CuI film was formed by spin coating from CuI NP acetonitrile solution. The root-mean-square roughness of the film reduced from 2.25 nm for spin coating from bulk CuI acetonitrile solution to 0.65 nm for CuI NPs. The power conversion efficiency of PSCs increased from 3.10% to 3.47% for CuI NP HTL. Moreover, the CuI NPs-based device demonstrated enhanced stability. The higher efficiency and better stability of CuI NPs-based PSCs should be attributed to uniform surface morphology and reducing exciton quenching of the CuI/the photoactive layer interface. This work indicates that CuI NPs will be a novel promising hole transporting material for highly efficient and stable PSCs.

With the rapid improvement of perovskite solar cells (PSCs), long-life operational stability has become a major requirement for their commercialization. In this work, we devised a pristine cesium-formamidinium-methylammonium (termed as CsFAMA) triple-cation-based perovskite precursor solution into the ionic liquid (IL)-assisted MAPbI3 nanoparticles (NPs) through a seeded growth approach in which the host IL-assisted MAPbI3 NPs remarkably promote high-quality perovskite films with large single-crystal domains, enhancing the device performance and stability. The power conversion efficiency (PCE) of the MAPbI3 NP-seeded growth of MAPbI3 NPs/CsFAMA-based PSCs is as high as 19.44%, which is superior to those of MAPbI3 NPs and pristine CsFAMA films as the photoactive layer (9.52 and 17.33%, respectively). The long-term light-soaking and moisture stability of IL-aided MAPbI3 NPs/CsFAMA-based devices (non-encapsulated) remain above 90 and 80%, respectively, of their initial output after 2 h of light illumination (1 sun) and 6000 h storage at ambient with a relative humidity range of 30-40%. The use of the IL-assisted MAPbI3 NP-seeded growth for PSCs is a significant step toward developing stable and reliable perovskite photovoltaic devices.

ConspectusConjugated polymers for application in organic solar cells (OSCs) have been developed from poly(phenylenevinylene) to poly(3-hexylthiophene) and then to "donor-acceptor" structures, providing power conversion efficiencies (PCEs) over 18% when blending with the electron acceptor as a two-component photoactive layer. Besides, graft-structural double-cable conjugated polymers that use an electron donor as conjugated backbones and an electron acceptor as pendant side units are one kind of conjugated polymer, in which charge carriers are generated in a single polymer. Therefore, double-cable conjugated polymers can be used as a single photoactive layer in single-component OSCs (SCOSCs). The covalently linked electron donor and acceptor enable double-cable polymers to maintain stable microstructures during long-term operation compared to two-component systems, which is very important for OSCs toward large-area applications. However, SCOSCs based on double-cable conjugated polymers provided PCEs below 3% in a long period, which is lagging far behind PCEs of two-component OSCs. The key reason for this is the limited number of chemical structures and the difficulty to tune the morphology in these polymers.In this Account, we provide an overview about our efforts on developing new double-cable conjugated polymers with rylene diimides as side units, and how to realize high PCEs in SCOSC devices. The studies start from developing a "functionalization-polymerization" method to synthesize the polymers containing rylene diimide acceptors, so that large amounts of double-cable conjugated polymers with distinct physical and electrochemical properties were obtained. Then, we will discuss how to control the nanophase separation in the crystalline region and optimize the miscibility in the amorphous region of double-cable polymers, simultaneously facilitating exciton dissociation and charge transport. With these efforts, a high PCE of 8.4% has been obtained, representing the record PCE in SCOSCs. In addition, the physical process and the stability of SCOSCs will be discussed. We hope that this account will inspire many innovative studies in this field and push the PCEs of SCOSCs to a new stage.

Side-chain engineering is an important strategy in designing novel polymer semiconductor materials for high-efficient organic solar cells. The use of trialkylsilyl side chains can improve the photovoltaic efficiency by decreasing the energy of the highest occupied molecular orbital (HOMO) of the polymer and improving its crystallinity and hole mobility. Compared to simple linear derivatives, α-branching in the alkyl groups of trialkylsilyl side chains causes strong aggregation and excessive phase separation in the photoactive layer, leading to poor device performance. β-branching of the alkyl groups has not yet been used in trialkylsilyl side chains. Herein, we describe a new polymer (J77) with triisobutylsilyl side chains to investigate the effect of β-branching on the molecular aggregation, optical properties, energy levels, and photovoltaic properties. We find that compared to α-branching, β-branching of alkyl groups in trialkylsilyl side chains significantly reduces aggregation. This enables J77 to form blend morphologies in films that provide high-efficient solar cells in combination with different non-fullerene acceptors. Moreover β-branching of the alkyl groups in trialkylsilyl side chains lowers the HOMO energy level of J77 and increases the open-circuit voltage of J77-based solar cells without sacrificing short-circuit current density or fill factor

For the commercialization of organic solar cells (OSCs), the fabrication of large-area modules via a solution process is important. The fabrication of OSCs via a solution process using a nonfullerene acceptor (NFA)-based photoactive layer is limited by the energetic mismatch and carrier recombination, reducing built-in potential and effective carriers. Herein, for the fabrication of high-performance NFA-based large-area OSCs and modules via a solution process, hybrid hole transport layers (h-HTLs) incorporating WO3 and MoO3 are developed. The high bond energies and electronegativities of W and Mo atoms afford changes in the electronic properties of the h-HTLs, which can allow easy control of the energy levels. The h-HTLs show matching energy levels that are suitable for both deep and low-lying highest occupied molecular orbital energy level systems with a stoichiometrically small amount of oxygen vacancies (forming W6+ and Mo6+ from the W5+ and Mo5+), affording high conductivity and good film forming properties. With the NFA-based photoactive layer, a large-area module fabricated via the all-printing process with an active area over 30 cm2 and a high power conversion efficiency (PCE) of 8.1% is obtained. Furthermore, with the h-HTL, the fabricated semitransparent module exhibits 7.2% of PCE and 22.3% of average visible transmittance with high transparency, indicating applicable various industrial potentials.

Interfacial layers in conjunction with suitable charge-transport layers can significantly improve the performance of optoelectronic devices by facilitating efficient charge carrier injection and extraction. This work uses a neat C60 interlayer on the anode to experimentally reveal that surface recombination is a significant contributor to nonradiative recombination losses in organic solar cells. These losses are shown to proportionally increase with the extent of contact between donor molecules in the photoactive layer and a molybdenum oxide (MoO3) hole extraction layer, proven by calculating voltage losses in low- and high-donor-content bulk heterojunction device architectures. Using a novel in-device determination of the built-in voltage, the suppression of surface recombination, due to the insertion of a thin anodic-C60 interlayer on MoO3, is attributed to an enhanced built-in potential. The increased built-in voltage reduces the presence of minority charge carriers at the electrodes-a new perspective on the principle of selective charge extraction layers. The benefit to device efficiency is limited by a critical interlayer thickness, which depends on the donor material in bilayer devices. Given the high popularity of MoO3 as an efficient hole extraction and injection layer and the increasingly popular discussion on interfacial phenomena in organic optoelectronic devices, these findings are relevant to and address different branches of organic electronics, providing insights for future device design.

In the present paper, we report the studies on perovskite (CH3NH3PbI3): Zinc Oxide (ZnO) bulk heterojunction (BHJ) photoactive layer (with two different ZnO concentrations) based solar cells fabricated under ambient air. ZnO and NiOx layers are used as the electron and hole transport layers respectively. The typical cell parameters of CH3NH3PbI3: ZnO BHJ solar cells have been calculated and analysed in comparison to that of solar cell fabricated with pristine perovskite (CH3NH3PbI3) based photoactive layer. The best performing solar cell (CH3NH3PbI3:ZnO; 1 mg/ml) has demonstrated highest power conversion efficiency (PCE) of 8.97% and retained 83.82% of its original value after 30 days under ambient air.

Among Renewable energy resources, solar power generation plays an important role and is paid more attention by modern researchers. Nowadays, extensive research is being carried to increase the efficiencies and stability of thin-film solar cells. Among thin-film solar cells, organic solar cells also known as plastic solar cells are relatively cheaper. They can be made in different colors and are very light in weight. These solar cells can be included in infrastructure such as windows, walls, car windshields, etc. Carbon nanotubes (CNTs) have some extraordinary properties such as high conductivity, high mechanical strength, and high aspect ratio along with the best physical and chemical properties. In this research, multi-walled carbon nanotubes (MWCNTs) with different concentration (1 to 5%) have been incorporated in the active layer of organic solar cells (OSCs), and improvement in short circuit current is reported. CNTs come along with entanglement and poor solubility. Ultra-sonication technique is used for dispersion and covalent functionalization technique is applied to increase the solubility of nonotubes.

Molecular ordering within the photoactive layer plays a crucial role in determining the device performance of organic solar cells (OSCs). However, the simultaneous molecular ordering processes of polymer donors and non-fullerene acceptors (NFAs) during solution casting usually bring confinement effect, leading to insufficient structural order of photovoltaic components. Herein, the molecular packing of m-INPOIC NFA is effectively formed through a heating induced aggregation strategy, with the aggregation of PBDB-T, which has a strong temperature dependence, is retarded by casting on a preheated substrate to reduce its interference toward m-INPOIC. A sequent thermal annealing treatment is then applied to promote the ordering of PBDB-T and achieve balanced aggregation of both donors and acceptors, resulting in the achievement of a maximum efficiency of 13.9% of PBDB-T:m-INPOIC binary OSCs. This work disentangles the interactions of donor polymer and NFA during the solution casting process and develops a rational strategy to enhance the molecular packing of NFAs to boost device performance.

Dye-sensitized solar cells (DSSCs) have attracted significant interest in the scientific community in recent years due to their advantages such as low fabrication cost, facile fabrication and capability to increase the DSSC performance. Up to date, there are a lot of efforts that have been performed to enhance the DSSC performance by introducing compact layers (CLs) and light scattering layer (LSLs) at the TiO2 photoactive layer. The CLs can reduce the recombination effect by preventing direct contact between transparent conductive oxide substrates and redox electrolytes. The CLs can reduce current leakage and generate more photocurrent and voltage, resulting in high DSSC performance. The performance of DSSCs also can be improved via the addition of LSLs. The LSLs must be larger than the titanium dioxide (TiO2) nanoparticles (typical photoanode in DSSCs) to trap more incident light and can excite more electrons, producing high power conversion efficiency. This review will be focused on the modification of the TiO2 photoactive layer by introducing CLs and LSLs to reduce the recombination effect and increase the light scattering effect for enhancing the DSSC performance. This review highlights various approaches and morphologies to prepare the CLs and LSLs using metal oxides and carbon-based materials.

With the surge of the power conversion efficiencies (PCEs) of organic solar cells (OSCs) in recent years, the commercialization of OSCs calls for scalable and environmentally friendly manufacturing techniques. Aerosol printing is a non-contact material deposition method that is compatible with flexible or curved substrates for scaled-up OSC fabrication. Here, by introducing vibrating mesh atomization (VMA) with specific engineering, we demonstrate the first attempt of fabricating OSCs by aerosol printing with the state-of-the-art OSC material of PTQ10:Y6-BO with an environmentally friendly solvent of o-xylene in ambient air. The inks of functional organic materials are converted by VMA into tiny aerosol droplets of ∼5 micrometers, which are passed through a slit printing nozzle to increase the droplet mass flux and suppress the coffee-ring effect. In doing so, favorable arrangement/crystallization of the organic molecules in photoactive layer are realized, leading to OSC devices with PCE up to 15.65%. The VMA is also suitable for printing the hole transport layer and electron transport layer. The all-aerosol-printed OSC devices achieved a PCE of 14.78%. Notably, VMA requires as little as 100 μL solution to prime the fluid lines, making the transition from laboratory experiments to continuous production more economical and practical. To illustrate this advantage, a mini automated production line was built to demonstrate the completion of five steps (printing of three functional layers, and thermal annealing of the hole transport layer and active layer) on a conveyer belt within 30 minutes, marking a concrete step towards manufacturing of high-performance OSCs.

In recent times the perovskite solar cells (PVSCs) have emerged as the most preeminent candidates among renewable technologies, yet the instability of PVSCs under ambient conditions has hindered their progress towards commercialization. Herein, a multifunctional passivation additive, 5-fluoropyrimidine-2,4(1H,3H)-dione (FPD), widely used as a cancer drug, was incorporated into the perovskite-based photoactive layer to enhance its photovoltaic efficiency along with its ambient stability. When this biologically active cancer drug molecule was utilized as a passivation additive, significant improvement was achieved in all the photovoltaic parameters, which collectively contributed to the enhancement of photovoltaic efficiency. The efficiency of PVSCs was elevated up to 20.22% for the FPD-passivated devices from 15.10% for the pristine device without any passivation. Furthermore, the incorporation of FPD also improved the long term durability of PVSCs by suppressing defects and enhancing the hydrophobicity of the perovskite surface. The FPD-passivated device maintained the PCE up to 89% in comparison to 27% for the pristine devices when PVSCs were exposed to a relative humidity of 45 ± 5% for 1000 h. This unique approach has elucidated the impact of passivation, which significantly enhanced the efficiency and long term stability to widen the possibility of practical applications.