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Highly sensitive strain sensors have been widely used in human motion monitoring, medical treatment, soft robots, and human–computer interaction, and the recycling of functional materials is in a huge demand for eco‐friendly and sustainable electronics. However, the manufacturing of recyclable strain sensors still remains challenging. Here, a semi‐wrapped structure based on silver nanowires and polyvinyl alcohol is proposed to realize a recyclable and stable strain sensor. It has shown excellent sensitivity, fast response, high stretchability and good environmental stability, and is successfully applied for human motion monitoring. In addition, a simple strategy is developed to effectively recycle silver nanowires in an eco‐friendly manner. The recyclable and stable strain sensor demonstrates potential applications in wearable and stretchable electronics, and the recycling strategy can be extended to other noble metal nanomaterials. [ABSTRACT FROM AUTHOR]

As an electron transport layer (ETL) widely used in organic solar cells (OSCs), ZnO has problems with energy level mismatch with the active layer and excessive defects on the ZnO surface, which can reduce the efficiency of OSCs. Here, ZnO/ZrSe2 composite is fabricated by modifying ZnO with 2D ZrSe2. The XPS and first‐principles calculation (FPC) show that ZnO obtains electrons from ZrSe2 and forms interfacial dipoles toward the active layer, which decreases the work function of ZnO, thus reducing the interface barrier and favoring the collection of electrons in OSCs. At the same time, after ZrSe2 modification, the oxygen vacancy density on the ZnO surface decreases, thus improving the conductivity of ZnO. More importantly, the femtosecond transient absorption (Fs‐TA) shows that ZrSe2 selectively traps holes from the active layer, which prevents the holes from entering the ZnO, thereby reducing the probability of electron recombination. Finally, ZnO/ZrSe2 composite is used as a novel ETL in OSCs with PBDB‐T: ITIC, PM6:Y6 and PM6: L8‐BO as active layers, and obtaining 12.09%, 16.34%, and 18.24% efficiency, respectively. This study provides a method for the interface modification of ZnO, and further investigates the role of 2D nanosheets in the interface modification. [ABSTRACT FROM AUTHOR]

The interface of perovskite solar cells (PSCs) plays an important role in transferring and collecting charges. Interface defects are important factors affecting the efficiency and stability of PSCs. Here, the buried interface between SnO2 and the perovskite layer is bridged by two‐dimensional (2D) MBene, which improves charge transfer. MBene can deposit additional electrons on the surface of SnO2, passivate its surface defects and facilitate the charge collection. Moreover, the dipole moment formed at the interface increases the electron transfer ability in the PSCs. MBene also regulates the growth of perovskite crystals, improves the quality of perovskite films, and reduces its grain boundary defects. As a result, PSCs based on FA0.2MA0.8PbI3 and (FAPbI3)0.95(MAPbBr3)0.05 get the enhanced efficiencies of 22.34 % and 24.32 % with negligible hysteresis. Furthermore, the optimized device exhibits better stability. This work opens up the application of MBene materials in PSCs, reveals a deeper understanding of the mechanism behind using 2D materials as an interface modification layer, and shows opportunities for using MBene as potential material in photoelectric devices. [ABSTRACT FROM AUTHOR]

Perovskite solar cells (PSCs) have been developing rapidly in recent years, in which the choice of additives plays a crucial role. Herein, a new small molecule is introduced named 5‐ADI with amino and carbonyl groups as an additive for perovskite. Specifically, the carbonyl group in 5‐ADI can interact with undercoordinated Pb2+ to passivate the perovskite defects. Moreover, the amino group can effectively immobilize I− atoms and inhibit ion migration, and it can synergistically passivate defects and improve photovoltaic performance. Meanwhile, the 5‐ADI treatment makes energy levels match well. Consequently, high‐quality perovskite film with fewer defects is produced due to 5‐ADI treatment improves the crystallinity of perovskite. The device fabricated with 5‐ADI additive achieves a power conversion efficiency of 22.42%. Besides, 5‐ADI can act as a barrier against water to promote perovskite moisture stability. In general, a superior strategy for defect passivation in PSCs is provided. [ABSTRACT FROM AUTHOR]

The energy loss (Eloss) aroused by inefficient charge transfer and large energy level offset at the buried interface of p‐i‐n perovskite solar cells (PVSCs) limits their development. In this work, a BF4− anion‐assisted molecular doping (AMD) strategy is first proposed to improve the charge transfer capability of hole transport layers (HTLs) and reduce the energy level offset at the buried interface of PVSCs. The AMD strategy improves the carrier mobility and density of poly[bis(4‐phenyl) (2,4,6‐trimethylphenyl) amine] (PTAA) and poly[N,N′‐bis(4‐butilphenyl)‐N,N′‐bis(phenyl)‐benzidine] (Poly‐TPD) HTLs while lowering their Fermi levels. Meanwhile, BF4− anions regulate the crystallization and reduce donor‐type iodine vacancies, resulting in the energetics transformation from n‐type to p‐type on the bottom surface of perovskite film. The faster charge transfer and formed p–n homojunction reduce charge recombination and Eloss at the HTL/perovskite buried interface. The PVSCs utilizing AMD treated PTAA and Poly‐TPD as HTLs demonstrate a highest power conversion efficiency (PCE) of 24.26% and 22.65%, along with retaining 90.97% and 85.95% of the initial PCE after maximum power point tracking for 400 h. This work provides an effective way to minimize the Eloss at the buried interface of p‐i‐n PVSCs by accelerating charge transfer and forming p–n homojunctions. [ABSTRACT FROM AUTHOR]

In organic solar cells (OSCs), the crystalline morphologies of the donor and acceptor at the microscale play an important role. 2D GeSe with periodic structure and high carrier mobility is an ideal additive material for active layer of OSCs that can effectively improve the crystallinity and molecular orientation of the acceptor molecule ITIC. Here, 2D GeSe is introduced into the active layer of OSCs to adjust the morphology of active layer for the first time, the results show that the incorporation of 2D GeSe induces the crystallization of acceptor molecule and facilitates the formation of efficient bicontinuous interpenetrating charge transport networks, and effectively reduces carrier recombination in OSCs. The power conversion efficiency and lifetime of OSCs are obviously enhanced. More importantly, the results of first‐principles calculation reveal that the interaction between 2D GeSe and ITIC guides the ITIC molecules to form a continuous conductive network. This study provides a method for the morphology regulation of the donor and acceptor domains in bulk heterojunctions, provides an idea for researching the interaction between 2D materials and organic molecules, and also indicates that 2D GeSe has good application prospects in photovoltaic devices. [ABSTRACT FROM AUTHOR]

The severe nonradiative recombination losses limit the further improvement of open‐circuit voltage (Voc) and power conversion efficiency (PCE) of perovskite solar cells (PVSCs). In this work, the 4,4′‐cyclohexylidenebis [N,N‐bis(4‐methylphenyl) benzene amine] is dissolved into the antisolvent to prepare perovskite films, which reduces defects, improves the crystallinity, and induces a p/p+ homojunction on the top surface of perovskite film. Besides, the 2‐thiophenemethylammonium iodide and 2‐thiophenethylammonium iodide form interface electric field and passivate defects on the bottom surface of perovskite film. The p/p+ homojunction and interface electric field enhance the charges' separation and transportation efficiencies in the bulk perovskite film and at the perovskite/charge transport layer interfaces, which effectively reduces nonradiative recombination losses and Voc loss of PVSCs. Consequently, low Voc loss of 0.348 V is realized, resulting in the increase in Voc from 1.082 to 1.172 V and PCE from19.15% to 23.44%. The optimized PVSCs without encapsulation maintain 88.23% of the original PCE after exposing in the air for 1500 h. This work provides a strategy to reduce the nonradiative recombination losses and Voc loss by forming p/p+ homojunction and interface electric field on the surfaces of perovskite film, which advances the development of high‐performance PVSCs. [ABSTRACT FROM AUTHOR]

The rapid development of perovskite solar cells (PSCs) perovskite is inseparable from the investigation of plentiful new additive materials. Herein, a conjugated organic material called TPD‐Br containing two carbonyl groups and Br atoms is synthesized. TPD‐Br with Lewis‐base groups can provide excellent passivation for defects between perovskite layer and electron transport layer. Furthermore, Br atom can also interact with iodine ions via halogen bonds. TPD‐Br passivates the perovskite defects because it can interact with undercoordinated Pb2+ ions by forming PbO bond, lower defect density and larger grain size occur in the perovskite can be obtained. Consequently, high‐quality perovskite films with fewer defects can be fabricated. The PSCs with TPD‐Br additive achieve a champion power conversion efficiency of 20.74%. These results illustrate that TPD‐Br, as a superior passivate defect additive, can improve the performance and stability of PSCs. [ABSTRACT FROM AUTHOR]

Perovskite solar cells have shown great potential in commercial applications due to their high performance and easy fabrication. However, the electron transport layer (ETL) materials with good optoelectrical properties and energy levels matching that of the perovskite layer still need to be explored to meet the need of commercialization. In this work, 2D Nb2CTx MXene nanosheets are prepared and their work function (WF) is reduced from 4.65 to 4.32 eV to match the conduction band minimum of perovskite layer by replacing the surface ‐F groups with NH2 groups through hydrazine (N2H4) treatment. Besides, the N2H4 treated (T‐Nb2CTx) MXene nanosheets with abundant NH2 groups are incorporated into the perovskite precursor to retard the crystallization rate by forming hydrogen bond with iodine ions, which promotes the formation of high‐quality and oriented growth perovskite films. Consequently, the PVSCs with T‐Nb2CTx MXene ETLs and T‐Nb2CTx MXene nanosheets additive exhibit the highest power conversion efficiency (PCE) of 21.79% and the corresponding flexible and large‐area devices achieve the highest PCE of 19.15% and 18.31%. Meanwhile, the unencapsulated devices maintain 93% of the original PCEs after 1500 h of storage. This work demonstrates the considerable application prospects of 2D Nb2CTx MXene in photoelectric devices. [ABSTRACT FROM AUTHOR]

Herein, a 2D α‐In2Se3 nanosheet, a binary III–VI group compound semiconductor, is fabricated by liquid‐phase exfoliation method, and the photoelectric properties of α‐In2Se3 material are investigated in depth. It is found that α‐In2Se3 film exhibits significant conductivity, outstanding optical transmission, and a suitable work function. Combined with its smooth surface and preferable hydrophobicity, α‐In2Se3 film can efficiently facilitate hole transporting in the polymer solar cells (PSCs). Due to the aforesaid advantages, a 2D α‐In2Se3 nanosheet is used as a hole transport layer (HTL) in conventional PSCs for the first time, and a relatively high power conversion efficiency (PCE) of 9.58% is achieved with the structure of ITO/α‐In2Se3/PBDB‐T:ITIC/Ca/Al, which is comparable with poly(3,4‐ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS)‐based devices (9.50%). Interestingly, it is demonstrated that the α‐In2Se3 film possesses excellent thermal stability in the range from room temperature to 280 °C, and a PCE of 9.35% is achieved without annealing treatment of α‐In2Se3 film, which exhibits a great potential of α‐In2Se3 for an annealing‐free approach. Furthermore, the incorporation of α‐In2Se3 HTL also remarkably enhances the long‐term stability of PSCs compared with PEDOT:PSS‐based devices. So, the results show that 2D α‐In2Se3 is a promising candidate to be an efficient and stable hole‐extraction layer. [ABSTRACT FROM AUTHOR]

Molecular doping of organic semiconductor is a great strategy for significantly regulating the electronic band structure of organic semiconductor while increasing charge mobility and carrier concentration. Here, a facile strategy is presented by introducing 2D g‐C3N5 as a p‐dopant into PM6, improving the charge mobility and hole carrier concentration of PM6. Moreover, the electron transfer between PM6 and g‐C3N5 can effectively downshift the Fermi energy level and highest occupied molecular orbital (HOMO) energy level of PM6, which leads to the increase the built‐in electric field of organic solar cells (OSCs). The addition of g‐C3N5 also effectively enhances the crystallization of active layer, thereby improving the stability of OSCs. As a result, a champion bulk‐heterojunction (BHJ) and layer‐by‐layer (LbL) structure OSCs are successfully achieved featuring a high‐power conversion efficiency of 18.10%/18.25%, simultaneously having excellent device stability. This work shows that introducing a low concentration dopant into organic donor is an effective method for improving the electrical performance of organic donor and the efficiency of OSCs. [ABSTRACT FROM AUTHOR]

Abstract: Spinterface engineering has shown quite important roles in organic spintronics as it can improve spin injection or extraction. In this study, 11,11,12,12‐tetracyanonaptho‐2,6‐quinodimethane (TNAP) is introduced as an interfacial layer for a prototype interface of Fe/TNAP. An element‐specific investigation of the electronic and magnetic structures of Fe/TNAP system by use of near edge X‐Ray absorption fine structure (NEXAFS) and X‐ray magnetic circular dichroism (XMCD) is reported. Strong hybridization between TNAP and Fe and induced magnetization of N atoms in TNAP molecule are observed. XMCD sum rule analysis demonstrates that the adsorption of TNAP reduces the spin moment of Fe by 12%. In addition, induced magnetization in N K‐edge of TNAP is also found with other commonly used ferromagnets in organic spintronics, such as La0.7Sr0.3MnO3 and permalloy, which makes TNAP a very promising molecule for spinterface engineering in organic spintronics. [ABSTRACT FROM AUTHOR]

Efficient bulk heterojunction (BHJ) polymer solar cells (PSCs) based on P3HT:PC70BM were fabricated by optimizing the processing parameters. The optimized thickness and annealing temperature have been found to be about 200 nm and 130°C. The effect of cathode interfacial layers on device performance is related to the formation of interfacial dipole. Furthermore, the effect of optimum ZnO interfacial thickness (~30 nm) on device performance is attributed to good interfacial conductivity and its optical property. The metal electrode deposited in the slow rate has a better influence on device performance. Based on these optimal conditions, the best power conversion efficiency (PCE) of 3.91% was obtained under AM 1.5G and 100 mW/cm2 illumination. This detailed investigation provides an important reference for the fabrication and optimization of polymer photovoltaic devices. [ABSTRACT FROM AUTHOR]

The interfaces of each layer in perovskite solar cells (PSCs) have a significant impact on the charge transfer and recombination. Especially, the interface between perovskite and the hole transport layer (HTL) in p‐i‐n type PSCs significantly affects the contact characteristics between the HTL and perovskite, hindering further improvements in performance and stability. Herein, a small molecule 9‐Fluorenylmethoxycarbonyl chloride (9‐YT) is introduced as a molecule bridge for p‐i‐n PSCs, which enhances the interaction between self‐assembly molecules (SAMs) and perovskite. The conjugated backbone of 9‐YT can interact with the SAM molecule (MeO‐2PACz) by π–π stacking reaction. Moreover, 9‐YT also improves the interfacial contact through strong interactions with the perovskite, where the carbonyl groups and Cl atoms in 9‐YT interact with uncoordinated Pb2+ in perovskite layer. The incorporation of a molecule bridge is demonstrated to markedly enhance hole extraction at the perovskite/hole transport layer interface, optimize energy level alignment, mitigate interface charge recombination, and passivate the uncoordinated Pb2+ and defects in the perovskite. Finally, the device treated with 9‐YT achieves a power conversion efficiency (PCE) of 24.82%. At the same time, PSCs can still maintain 92.6% of the original PCE after a long‐term stability test of 1200 h. [ABSTRACT FROM AUTHOR]

High‐performance perovskite solar cells (PSCs) fabricated in ambient air are considered inevitable for low‐cost commercial manufacturing. However, passivating perovskite film defects and controlling the crystallization process are critical for achieving high performance in PSCs. This study proposes using the novel 2D material MBene in green antisolvent to simultaneously modulate the crystallization and passivation defects of perovskites. MBene facilitates the passivation of uncoordinated Pb2+ ions, thereby enhancing the formation energy of vacancies within the perovskite film and adjusting the energy level structure. Moreover, MBene increases nucleation sites for perovskite, significantly extending crystal growth and improving film crystallinity, thereby reducing non‐radiative recombination. Consequently, champion devices treated with MBene achieve a power conversion efficiency (PCE) of 24.22% when fabricated in air, and exhibit superior humidity and long‐term stability. Furthermore, PSCs with added MBene exhibit significant long‐term stability under various environmental conditions, including humidity and heat. The study results lay a foundation for the development of MBene materials in photovoltaics, revealing their mechanism as a new type of 2D material in perovskites, and providing new insights for industrially producing efficient and stable solar cells. [ABSTRACT FROM AUTHOR]