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The development of inverted all-inorganic perovskite solar cells (PSCs) is limited by the high processing temperature and poor film coverage of self-assembled molecule (SAM) hole transport layer (HTL). In this work, the hot-air-assisted annealing method was utilized to prepare CsPbI2Br films at low temperature in an ambient environment. The SAM called 2–(3,6-dimethoxycarbazol-9-yl) ethyl phosphonic acid (MeO-2PACz) is added into the CsPbI2Br precursor to spontaneously form MeO-2PACz dipole layer and perovskite light absorber. The MeO-2PACz with abundant phosphate groups modulated the uncoordinated lead at the perovskite's grain boundaries via forming –P–O–Pb and –P=O–Pb bonds, which improves the crystallinity and reduces trap density of perovskite film. Furthermore, the spontaneously formed MeO-2PACz dipole layer on the ITO substrate during the perovskite film processing enhanced hole transport efficiency and reduced non-radiative recombination loss at the ITO/CsPbI2Br interface. As a result, the p-i-n HTL-free inorganic CsPbI2Br PSCs with MeO-2PACz additive achieved a power conversion efficiency of 12.92%, which is significantly higher than the reference PSCs (6.55%). This work provides an easy and efficient way to prepare efficient HTL-free all-inorganic PSCs at low temperature in an ambient environment with MeO-2PACz SAM additive. [ABSTRACT FROM AUTHOR]

As an electron transport layer (ETL) widely used in organic solar cells (OSCs), ZnO has issues with energy level mismatch with the active layer and excessive surface defects, which ultimately reduce the efficiency of OSCs. Here, a ZnO:NADH ETL is prepared by modifying ZnO with green biomaterial nicotinamide adenine dinucleotide (NADH). XPS and UPS show that ZnO obtains electrons from NADH and decreases the work function of ZnO, thus lowering the interface barrier between ZnO and the active layer, which is conducive to electron collection in OSCs. At the same time, the oxygen vacancy density on the ZnO surface reduces after modification with biomaterial NADH, thus improving the electrical conductivity of ZnO. Finally, we use PM6:Y6 and PM6:L8-BO as active layers, and use ZnO:NADH as a novel ETL in OSCs, achieving efficiencies of 16.77% and 18.21%, respectively. The stability of the device with the ZnO:NADH ETL has also been improved to a certain extent. This study provides an effective method for ZnO modification, and also contributes to the environmental protection in the device preparation process. [ABSTRACT FROM AUTHOR]

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]

Inhibiting metal electrode corrosion and reducing cathode interface charge loss are of significant importance for achieving stable and efficient p-i-n perovskite solar cells (PVSCs). Herein, two-dimensional (2D) thiol-functionalized covalent organic frameworks (SH-COFs) are used as an advanced barrier layer to provide an integrated solution for the above issues. The SH-COF rich in thiol groups can form close contact with the surface of Ag electrodes due to its strong chemical coordination, thus improving the corrosion resistance of metal electrodes. The inserted SH-COF interlayer also effectively hinders the ion migration and chemical reaction at the perovskite/metal electrode interface. Meanwhile, the SH-COF interlayer provides optimized interface contact and a cascade energy band arrangement, which is beneficial for promoting electron extraction and reducing non-radiative recombination at the cathode interface. Therefore, SH-COF-modified inverted PVSCs achieve power conversion efficiencies (PCEs) of 24.12% and 21.63% for 0.15 cm2 and 1 cm2-sized devices. Moreover, the optimized devices retain 93.3% and 90.7% of their initial PCEs after aging at 85 °C for 1200 h and maximum power point tracking at 65 °C for 1000 h, respectively. This work provides a promising strategy for overcoming the performance and long-term stability limitations of p-i-n PVSCs to promote their commercialization by SH-COF-modification. [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]

In organic solar cells (OSCs), ZnO is a widely used electron transport layer (ETL), but various vacancy defects on the surface of ZnO crystals form massive trap-assisted recombination centers, which hinders electron transmission in OSCs. In this paper, a ZnO&GeSe composite is constructed by modifying ZnO with two-dimensional (2D) GeSe, and it is used for the first time as a novel ETL in OSCs, which reduces the defect density on the ZnO surface and improves the electron extraction efficiency in OSCs. The results of first-principles calculations show that GeSe can deposit additional electrons on the surface of ZnO, which stabilizes the ZnO polar surface and reduces the formation of spontaneous defects on the ZnO polar surface. The electric dipole moment formed at the interface also promotes electron transport in OSCs. The power conversion efficiency (PCE) of OSCs based on PBDB-T:ITIC and PM6:Y6 active layers increases from 10.06% and 15.20% to 11.68% and 17.51%, respectively. Meanwhile, the OSC with the ZnO&GeSe composite ETL possesses good stability compared to the device with the pure ZnO ETL. This study shows that 2D GeSe has a good application prospect as a charge transport layer, and provides an idea for the defect modification of ZnO and other semiconductor crystals by 2D materials. [ABSTRACT FROM AUTHOR]