In situ carbon coating for enhanced chemical stability of copper nanowires

Copper nanowires(CuNWs)are promising electrode materials,especially for used in flexible and transparent electrodes,due to their advantages of earth-abundant,low-cost,high conductivity and flexibility.However,the poor stability of CuNWs against oxidation and chemic-al corrosion seriously hinders their practical applications.Herein,we propose a facile strategy to improve the chemical stability of CuNWs by in situ coating of carbon protective layer on top of them through hydrothermal carbonization method.The influential factors on the growth of carbon film including the concentration of the glucose precursor(carbon source),hydrothermal temperature,and hydrothermal time are sys-tematically studied.By tailoring these factors,carbon layers with thickness of 3-8 nm can be uniformly grown on CuNWs with appropriate glucose concentration around 80 mg·mL−1,hydrothermal temperature of 160-170°C,and hydrothermal time of 1-3 h.The as-prepared carbon-coated CuNWs show excellent resistance against corrosion and oxidation,and are of great potential to use broadly in various optoelectronic devices.

Facile Modification on Buried Interface for Highly Efficient and Stable FASn_(0.5)Pb_(0.5)I_(3) Perovskite Solar Cells with NiOx Hole-Transport layers

Formamidinium(FA)-based Sn-Pb perovskite solar cells(FAPb_(0.5)Sn_(0.5)I_(3) PSCs)with ideal bandgap and impressive thermal stability have caught enormous attention recently.However,it still suffers from the challenge of realizing high efficiency due to the surface imperfections of the transport materials and the energy-level mismatch between functional contacts.Herein,it is demonstrated that the modification on buried interface with alkali metal salts is a viable strategy to alleviate these issues.We systematically investigate the role of three alkali metal bromide salts(NaBr,KBr,CsBr)by burying them between the NiOx hole transport layer(HTL)and the perovskite light-absorbing layer,which can effectively passivate interface defects,improve energy-level matching and release the internal residual strain in perovskite layers.The device with CsBr buffer layer exhibits the best power conversion efficiency(PCE)approaching 20%,which is one of the highest efficiencies for FA-based Sn-Pb PSCs employing NiO_(x) HTLs.Impressively,the long-term storage stability of the unencapsulated device is also greatly boosted.Our work provides an efficient strategy to prepare desired FA-based ideal-bandgap Sn-Pb PSCs which could be applied in tandem solar cells.

2D materials for conducting holes from grain boundaries in perovskite solar cells

Grain boundaries in organic-inorganic halide perovskite solar cells(PSCs)have been found to be detrimental to the photovoltaic performance of devices.Here,we develop a unique approach to overcome this problem by modifying the edges of perovskite grain boundaries with flakes of high-mobility two-dimensional(2D)materials via a convenient solution process.A synergistic effect between the 2D flakes and perovskite grain boundaries is observed for the first time,which can significantly enhance the performance of PSCs.We find that the 2D flakes can conduct holes from the grain boundaries to the hole transport layers in PSCs,thereby making hole channels in the grain boundaries of the devices.Hence,2D flakes with high carrier mobilities and short distances to grain boundaries can induce a more pronounced performance enhancement of the devices.This work presents a cost-effective strategy for improving the performance of PSCs by using high-mobility 2D materials.