Sub‐second Lifetime of Photocarriers in Hybrid Lead Halide Perovskite

Abstract

Recently lead halide perovskite based solar cells have rapidly advanced and their power conversion efficiency (PCE) increased to 25.7%. The progress has been attributed to the super‐long carriers’ lifetime (τ) and long diffusion length (LD) of the photocarriers, however it has been a challenge to precisely characterize and understand the super‐long τ and LD of photocarriers. Here, a MAPbI3 single crystal exhibits four different τ which increase with LD extending from nm scale to mm scale. The prior two lifetimes estimated by transient photoluminescence (TPL) spectra are in the range of ns which comes from the recombination of photocarriers in the tens of nm thick surface layer. In contrast, the third lifetime estimated by transient open‐circuit voltage is hundreds of µs, which is a result of the excess photocarriers diffusing hundreds of µm to electrodes. Finally, the fourth lifetime estimated from the transient photoconductance is as long as sub‐second since the low‐density photocarriers under an electric field drift across the mm‐scale high‐quality single crystal. This study not only clarifies the physical mechanisms of four different lifetimes of photocarriers but also facilitates the design of novel electronics with the halide perovskite semiconductors.

Ultrafast Multifunctional Photodetector Based on the NiAl2O4/4H-SiC Heterojunction

“…Multifunctional photodetectors (MPDs) based on semiconductor photoconductive and/or photovoltaic effects have received significant attention in recent years due to their dominance in space exploration, encrypted communication, and biomedical directional detection. − The position-sensitive detectors (PSDs) based on the lateral photovoltaic (LPV) effect − are a special type of PDs that can be used for the position detection of a light beam. In this context, the pivotal parameters defining PDs are their position sensitivity and relaxation time. − Self-powered ultraviolet MPDs based on SiC Schottky or p – n junctions have several advantages, including small size, high-speed operation, and excellent stability in harsh environments. − The position sensitivity of 67.8 mV/mm with a relaxation time of 30 μs had been observed in Fe 3 O 4 /3C-SiC Schottky junctions, but the long relaxation time restricts their practical applications . Liu et al observed a large position sensitivity (750.86 mV/mm) and ultrafast relaxation time (0.49 μs) in a triple-layer Ga 2 O 3 /NiO/SiC heterojunction, suggesting the importance of the built-in electric field in the junction for high-performance PSDs .…”