Search

The dynamic process of crystallization of nickel-tetrabenzoporphyrin (NTBP) from its amorphous precursor film was investigated. NTBP crystalline films with a preferential orientation were obtained through the recrystalization from its precursor film deposited on polyimide (PI) substrate. This preferential orientation, with (001) plane lies in the film plane, increases the in-plane electrical conductivity of the film dramatically in comparison with that deposited on a glass substrate where no preferential orientation was observed. Such a preferential orientation of NTBP is caused by the local order of the PI surface molecules which act as favorable nucleation sites to grow NTBP in preferential crystallographic direction. This view is supported by the observed lower activation energy (0.96 eV) required for continuing crystallization on PI than that on glass (1.27 eV). The time dependence of the nucleus density of NTBP follows N ~ t n , where n = 1 and 1.5 for PI and glass substrates, respectively. This can be interpreted as a result of lacking of nucleation centers on the glass substrate hence newly activated sites are required to continue the crystallization, while on the PI substrate such process is not required. [ABSTRACT FROM AUTHOR]

Abstract: Recent development of solution processable organic semiconductors delineates the emergence of a new generation of air-stable, high performance p- and n-type materials. This makes it indeed possible for printed organic complementary circuits (CMOS) to be used in real applications. The main technical bottleneck for organic CMOS to be adopted as the next generation organic integrated circuit is how to deposit and pattern both p- and n-type semiconductor materials with high resolutions at the same time. It represents a significant technical challenge, especially if it can be done for multiple layers without mask alignment. In this paper, we propose a one-step self-aligned fabrication process which allows the deposition and high resolution patterning of functional layers for both p- and n-channel thin film transistors (TFTs) simultaneously. All the dimensional information of the device components is featured on a single imprinting stamp, and the TFT-channel geometry, electrodes with different work functions, p- and n-type semiconductors and effective gate dimensions can all be accurately defined by one-step imprinting and the subsequent pattern transfer process. As an example, we have demonstrated an organic complementary inverter fabricated by 3D imprinting in combination with inkjet printing and the measured electrical characteristics have validated the feasibility of the novel technique. [Copyright &y& Elsevier]

Self‐assembled monolayers (SAMs) have significantly improved the device performance of inverted perovskite solar cells (PSCs). However, the inadequate chemical bonding affinity between SAMs and the substrate as well as the uneven SAM distribution can lead to the decrease in device performance. Herein, the study reports a bilayer NiOx hole transport layer (HTL), consisting of ultrathin NiOx buffer film prepared through atomic layer deposition (ALD‐NiOx) and spin‐coated NiOx film (Spin‐NiOx). The work function difference between the two NiOx films will facilitate the hole transfer from the ALD‐NiOx to the Spin‐NiOx in the ALD‐NiOx/Spin‐NiOx bilayer structure. These holes will undergo surface hydroxylation reactions with water molecules on the Spin‐NiOx film surface, generating additional hydroxyl groups covalently bonded to the Spin‐NiOx film, which can provide more anchoring sites for SAM molecules. Stable covalent bonds can be formed between the Spin‐NiOx film and the subsequently coated SAM film. As a result, SAM films with better coverage and molecular arrangement can be obtained. The ALD‐NiOx/Spin‐NiOx/SAM composite HTL also demonstrates superior charge transport capability and thermal stability. For small area PSCs (0.06 cm2) prepared by using the composite HTL, a champion power conversion efficiency (PCE) of 25.25% is achieved, and the device stabilities are also significantly improved. [ABSTRACT FROM AUTHOR]

The two-step layer-by-layer (LBL) deposition of donor and acceptor films enables desired vertical phase separation and high performance in organic solar cells (OSCs), which becomes a promising technology for large-scale printing devices. However, limitations including the use of toxic solvents and unpredictable infiltration between donor and acceptor still hinder the commercial production of LBL OSCs. Herein, we developed a water-based nanoparticle (NP) ink containing donor polymer to construct a mesoscale structure that could be infiltrated with an acceptor solution. Using non-halogen o-xylene for acceptor deposition, the LBL strategy with a mesoscale structure delivered outstanding efficiencies of 18.5% for binary PM6:L8-BObased LBL OSCs. Enhanced charge carrier mobility and restricted trap states were observed in the meso-LBL devices with optimized vertical morphology. It is believed that the findings in this work will bring about more research interest and effort on eco-friendly processing in preparation for the industrial production of OSCs. [ABSTRACT FROM AUTHOR]

All‐polymer solar cells (all‐PSCs) have promising potential for industrial production due to their superior stability. Recently, the widespread application of the polymerized small molecule acceptor (PSMA) has led to a surge in the efficiency of all‐PSCs. However, the high efficiencies of these devices generally rely on the use of the highly volatile solvent, chloroform (CF). Furthermore, the molecular weights of PSMA are lower than polymer donors, yet their crystallinity is weaker than typical small molecules, making most PSMA‐based all‐PSCs suffer from low electron mobility. To improve device performance and facilitate large scale production of all‐PSCs, it is necessary to enhance electron mobility and avoid the use of CF. This paper investigates the use of sequential processing (SqP) for active layer preparation using toluene as the solvent to address these issues. This work reports 18.1% efficient all‐PSC devices, which is the highest efficiency of all‐PSCs prepared using non‐halogen solvents. This work systematically compares the conventional blend‐casting method with the SqP method using PM6 as the donor and PY‐V‐γ and PJ1‐γ as the acceptors, and compares the performance of binary and ternary blends in both methods. Finally, this work measures the device stability and finds that SqP can significantly improve the photostability of the device. [ABSTRACT FROM AUTHOR]

Organic solar cells (OSCs) have gained increasing attention. Among the various directions in OSCs, all-polymer solar cells (all-PSCs) have emerged as a highly promising and currently active research area due to their excellent film formation properties, mechanical properties, and thermal stabilities. However, most of the high-efficiency all-PSCs are processed from chloroform with an active layer thickness of ~100 nm. In order to meet the requirements for industrialization, a thicker active layer processed from low-vapor pressure solvents (preferentially a hydrocarbon solvent) is strongly desired. Herein, we employ toluene (a hydrocarbon solvent with a much higher boiling point than chloroform) and a method known as sequential processing (SqP) to mitigate the rapid decline in efficiency with increasing film thickness. We show that SqP enables a more favorable vertical phase segregation that leads to less trap-assisted recombination and enhanced charge extraction and lifetime than blend-cast devices at higher film thicknesses. [ABSTRACT FROM AUTHOR]

The electron transport layer (ETL) with excellent charge extraction and transport ability is one of the key components of high-performance perovskite solar cells (PSCs). SnO2 has been considered as a more promising ETL for the future commercialization of PSCs due to its excellent photoelectric properties and easy processing. Herein, we propose a facile and effective ETL modification strategy based on the incorporation of methylenediammonium dichloride (MDACl2) into the SnO2 precursor colloidal solution. The effects of MDACl2 incorporation on charge transport, defect passivation, perovskite crystallization, and PSC performance are systematically investigated. First, the surface defects of the SnO2 film are effectively passivated, resulting in the increased conductivity of the SnO2 film, which is conducive to electron extraction and transport. Second, the MDACl2 modification contributes to the formation of high-quality perovskite films with improved crystallinity and reduced defect density. Furthermore, a more suitable energy level alignment is achieved at the ETL/perovskite interface, which facilitates the charge transport due to the lower energy barrier. Consequently, the MDACl2-modified PSCs exhibit a champion efficiency of 22.30% compared with 19.62% of the control device, and the device stability is also significantly improved. [ABSTRACT FROM AUTHOR]

Water processing is an ideal strategy for the ecofriendly fabrication of organic photovoltaics (OPVs) and exhibits a strong market−driven demand. Here, we report a state−of−the−art active material, namely PM6:BTP−eC9, for the synthesis of water−borne nanoparticle (NP) dispersion towards ecofriendly OPV fabrication. The surfactant−stripping technique, combined with a poloxamer, facilitates purification and eliminates excess surfactant in water−dispersed organic semiconducting NPs. The introduction of 1,8−diiodooctane (DIO) for the synthesis of surfactant−stripped NP (ssNP) further promotes a percolated microstructure of the polymer and NFA in each ssNP, yielding water−processed OPVs with a record efficiency of over 11%. The use of an additive during water−borne ssNP synthesis is a promising strategy for morphology optimization in NP OPVs. It is believed that the findings in this work will engender more research interest and effort relating to water−processing in preparation of the industrial production of OPVs. [ABSTRACT FROM AUTHOR]

All-polymer solar cells (all-PSCs) are organic solar cells in which both the electron donor and the acceptor are polymers and are considered more promising in large-scale production. Thanks to the polymerizing small molecule acceptor strategy, the power conversion efficiency of all-PSCs has ushered in a leap in recent years. However, due to the electrical properties of polymerized small-molecule acceptors (PSMAs), the FF of the devices is generally not high. The typical electron transport material widely used in these devices is PNDIT-F3N, and it is a common strategy to improve the device fill factor (FF) through interface engineering. This work improves the efficiency of all-polymer solar cells through interfacial layer engineering. Using PDINN as the electron transport layer, we boost the FF of the devices from 69.21% to 72.05% and the power conversion efficiency (PCE) from 15.47% to 16.41%. This is the highest efficiency for a PY-IT-based binary all-polymer solar cell. This improvement is demonstrated in different all-polymer material systems. [ABSTRACT FROM AUTHOR]

All-polymer solar cells (All-PSCs), whose electron donor and acceptors are both polymeric materials, have attracted great research attention in the past few years. However, most all-PSC devices with top-of-the-line efficiencies are processed from chloroform. In this work, we apply the sequential processing (SqP) method to fabricate All-PSCs from an aromatic hydrocarbon solvent, toluene, and obtain efficiencies up to 17.0%. By conducting a series of characterizations on our films and devices, we demonstrate that the preparation of SqP devices using toluene can effectively reduce carrier recombination, enhance carrier mobility and promote the fill factor of the device. [ABSTRACT FROM AUTHOR]

Doctor-blade coating technology is a roll-to-roll compatible high-throughput thin film fabrication route. In this work, doctor-blading was applied for fabricating organic solar cells (OSCs) using a polyoxometalates material phosphomolybdic acid (PMA) as a hole transport layer (HTL). Compared to PEDOT:PSS, PMA-based devices demonstrate lower trap-assisted recombination, higher hole mobility, prolonged charge carrier lifetime and faster charge collection. With PM6:Y6 as active layer, PMA-based device delivered a high power conversion efficiency (PCE) of 17.79 % with a boosted short-circuit current density (J SC) value of 28.08 mA/cm2, which is one of the best performances for PM6:Y6-based solar cells through doctor-blading process. In addition, the performance improvement was observed in both conventional and inverted structured devices with various donor: acceptor combinations. These results indicate the high universality of PMA for printable processing and its prospect in preparation of the industrial production of OSCs. [Display omitted] • Phosphomolybdic acid (PMA) was introduced as a hole transport layer (HTL) in organic solar cells (OSCs). • PMA is compatible for both conventional and inverted structured devices. • The blade-coating processed OSCs based on PM6:Y6 achieved a high efficiency of 17.8 %. • One of the highest performance for PM6:Y6-based OSCs through blade-coating. [ABSTRACT FROM AUTHOR]

The ternary and additive strategy, introducing a third component into a binary blend and add suitable additives, opens a simple and promising avenue to improve the power conversion efficiency (PCE) of organic solar cells (OSCs). This study investigates the optimization of OSCs by introducing volatile additives and a third component, L8-BO-X, which tunes the active layer morphology and improves the performance of the devices. Utilizing various characterization techniques, such as the grazing-incidence wide-angle X-ray scattering (GIWAXS), film-depth-dependent light absorption spectroscopy (FLAS), and the femtosecond-resolved transient absorption (fsTA) spectroscopy, the effects of these adjustment on crystallinity, phase separation, exciton generation, and charge transport in photovoltaic device are explored. The incorporation of the third component and volatile additives results in less anisotropy in molecular orientation and thus faster exciton splitting at the D-A interface, enhanced π-π stacking coherence length and longer exciton lifetime, and eventually an enhanced power conversion efficiency (PCE) of 19.6 % (certified as 19.07 % in the National Institute of Metrology in China) and exceptional photostability, with the devices retaining 82 % efficiency after 1200 hours of continuous light exposure. [Display omitted] [ABSTRACT FROM AUTHOR]

In this work, we apply the sequential processing (SqP) method to address the relatively low electron mobility in recent all-polymer solar cells (all-PSCs) based on the polymerized small-molecule acceptor (PSMA). Compared to the blend-casting (BC) method, all-PSCs composed of PM6/PY-IT via the SqP method show boosted electron mobility and a more balanced charge carrier transport, which increases the FF of the SqP device and compensates for the short-circuit current loss, rendering comparable overall performance with the BC device. Through film-depth-dependent light absorption spectroscopy, we analyze the sub-layer absorption and exciton generation rate in the vertical direction of the device, and discuss the effect of the increased electron mobility on device performance, accordingly. [ABSTRACT FROM AUTHOR]

Spin–orbit torques (SOTs) in compensated ferrimagnets (FMs) have been widely studied due to their abundant advantages for the application in spintronic devices. Recently, the SOT in FM metals near compensation tuned by composition and temperature has been reported. However, the SOT in FM insulators (FMIs) near compensation still remains elusive. In this work, we report the study of the SOT in FMI near compensation tuned by the temperature. First, Pt/Gd3Fe5O12 (GdIG) bilayer films with high crystallinity and perpendicular magnetic anisotropy were fabricated by magnetron sputtering. Then, the SOT was measured by varying the temperature. It is found that the SOT generation is drastically enhanced close to the compensation temperature, which is verified to be caused by the decrease in the net magnetization. The effective spin Hall angle in Pt/GdIG bilayer films is estimated to be ∼0.0073, which is almost independent of the temperature. Our study provides a potential approach in emerging FMIs for spintronic devices with low-energy consumption. [ABSTRACT FROM AUTHOR]

An optically addressed spatial light modulator (OASLM) works by using the intensity of a 'write' light to modulate the phase of a 'read' light. OASLM using ZnO nanoparticles (NPs) as a photoconductor is important to holographic displays because of its record-high spatial resolution. However, its response time to the write light is long and the switch-off time (τoff) can take tens of seconds due to the trap states in the ZnO NP layer. This results in residual images and poses limitations to its application in dynamic holographic displays. In this work, a ZnO NP photoconductor was replaced by a solution-processed ZnO NP/PEDOT:PSS heterojunction photodiode and the τoff of OASLM was significantly reduced to about 0.6 s. Electrical and optical properties of the heterojunction were characterized and a barrier height of 0.604 eV was determined by CV measurement. The heterojunction-based OASLM was then fabricated and its light modulating performance was investigated by using a diffractive phase grating. Finally, impedance spectroscopy was used to analysis the device equivalent circuit and optimize the operation of the OASLM. [ABSTRACT FROM AUTHOR]

• The use of a TaN buffer layer significantly enhanced ASIC-integrated AMR sensor performance. • The presence of a PECVD-deposited SiO2 interlayer exerts a sensitivity deteriorating influence on AMR sensors. • Granular SiO2 surface structures is linked to increased anisotropy field and altered magnetic properties in AMR sensors. • Study offers insights into optimizing SiO2 formation for integration of magnetoresistive sensors and ASIC substrates. This study investigates the impact of a TaN buffer layer on the performance of ASIC-integrated Anisotropic Magnetoresistive (AMR) position sensors. Our findings demonstrate that the inclusion of a TaN buffer layer significantly enhances the sensitivity and stability of the sensors, with a measured sensitivity of 0.678 ± 0.03 Gauss/mV. In contrast, devices without the buffer layer exhibit a notable decline in sensitivity, decreasing to 0.165 ± 0.02 Gauss/mV after 450℃ annealing. In addition, AMR sensors fabricated on non-ASIC substrates showed no such deterioration. Magneto-optical Kerr effect (MOKE) measurements reveal that the change in sensitivity is primarily attributed to variations in the anisotropy field. We propose that the increased anisotropy field is a result of magnetostatic energy induced by alterations in the PECVD-deposited SiO2 surface granular structure, supported by surface morphology characterization and X-ray diffraction experiments. These findings highlight the critical role of the TaN buffer layer in optimizing the performance and stability of ASIC-integrated AMR sensors. [ABSTRACT FROM AUTHOR]

Wereport a study of enhancing the magnetic ordering in a model magneticallydoped topological insulator (TI), Bi2–xCrxSe3, via the proximityeffect using a high-TCferrimagnetic insulatorY3Fe5O12. The FMI provides the TIwith a source of exchange interaction yet without removing the nontrivialsurface state. By performing the elemental specific X-ray magneticcircular dichroism (XMCD) measurements, we have unequivocally observedan enhanced TCof 50 K in this magneticallydoped TI/FMI heterostructure. We have also found a larger (6.6 nmat 30 K) but faster decreasing (by 80% from 30 to 50 K) penetrationdepth compared to that of diluted ferromagnetic semiconductors (DMSs),which could indicate a novel mechanism for the interaction betweenFMIs and the nontrivial TIs surface. [ABSTRACT FROM AUTHOR]

• Strong PEB is obtained in the Pt/Co/MgO film. • The blocking temperature of the Pt/Co/MgO film is higher than that of the Pt/Co/CoO film. • MgO thickness has significant effect on the SOT generation. We study the perpendicular exchange bias (PEB) and spin-orbit torque (SOT) generation in the Pt/Co/MgO heterostructure by changing the thickness of the MgO layer. We show that the oxidation of the beneath Co layer increases with the MgO thickness. Strong PEB is obtained in the Pt/Co/MgO films, which exhibits a much higher blocking temperature compared with that in the Pt/Co/CoO films. Furthermore, it is found that the MgO thickness has significant effect on the SOT generation. Maximum values of the SOTs are obtained with a 0.8 nm-thick MgO layer, which decreases by increasing the MgO thickness from 0.8 to 1.6 nm. Our results shed a light on the essential role of the MgO layer in the heavy metal/ferromagnet/MgO heterostructure, a typical material system in spintronic devices, and provide a way to manipulate the magnetic properties and the SOTs by oxide layers. [ABSTRACT FROM AUTHOR]