Hole-Transporting Low-Dimensional Perovskite for EnhancingPhotovoltaic Performance

Halide perovskites with low-dimensionalities(2D or quasi-2D)have demonstrated outstanding stabilities compared to their 3D counterparts.Nevertheless,poor charge-transporting abilities of organic components in 2D perovskites lead to relatively low power conversion efficiency(PCE)and thus limit their applications in photovoltaics.Here,we report a novel hole-transporting low-dimensional(HT2D)perovskite,which can form a hole-transporting channel on the top surface of 3D perovskite due to self-assembly effects of metal halide frameworks.This HT2D perovskite can significantly reduce interface trap densities and enhance hole-extracting abilities of a heterojunction region between the 3D perovskite and hole-transporting layer.Furthermore,the posttreatment by HT2D can also reduce the crystal defects of perovskite and improve film morphology.As a result,perovskite solar cells(PSCs)can effectively suppress nonradiative recombination,leading to an increasement on photovoltage to>1.20 V and thus achieving>20%power conversion efficiency and>500 h continuous illumination stability.This work provides a pathway to overcome charge-transporting limitations in low-dimensional perovskites and delivers significant enhancements on performance of PSCs.

One-Dimensional(NH=CINH_(3))_(3)PbI_(5)Perovskite for Ultralow Power Consumption Resistive Memory

Organic-inorganic hybrid perovskites(OIHPs)have proven to be promising active layers for nonvolatile memories because of their rich abundance in earth,mobile ions,and adjustable dimensions.However,there is a lack of investigation on controllable fabrication and storage properties of one-dimensional(1D)OIHPs.Here,the growth of 1D(NH=CINH_(3))_(3)PbI_(5)((IFA)_(3)PbI_(5))perovskite and related resistive memory properties are reported.The solution-processed 1D(IFA)_(3)PbI_(5)crystals are of welldefined monoclinic crystal phase and needle-like shape with the length of about 6 mm.They exhibit a wide bandgap of 3 eV and a high decomposition temperature of 206℃.Moreover,the(IFA)_(3)PbI_(5)films with good uniformity and crystallization were obtained using a dual solvent of N,N-dimethylformamide(DMF)and dimethyl sulfoxide(DMSO).To study the intrinsic electric properties of this anisotropic material,we constructed the simplest memory cell composed of only Au/(IFA)_(3)PbI_(5)/ITO,contributing to a high-compacted device with a crossbar array device configuration.The resistive random access memory(ReRAM)devices exhibit bipolar current-voltage(I-V)hysteresis characteristics,showing a record-low power consumption of~0.2 mW among all OIHP-based memristors.Moreover,our devices own the lowest power consumption and“set”voltage(0.2 V)among the simplest perovskite-based memory devices(inorganic ones are also included),which are no need to require double metal electrodes or any additional insulating layer.They also demonstrate repeatable resistance switching behaviour and excellent retention time.We envision that 1D OIHPs can enrich the low-dimensional hybrid perovskite library and bring new functions to low-power information devices in the fields of memory and other electronics applications.