Solution-processed Perovskite Photodetectors Research Articles

Sub-millimetre light detection and ranging using perovskites

Light detection and ranging (LiDAR) technology is an active remote-sensing system used in autonomous vehicles, machine vision and augmented reality. Improvements in the speed and signal-to-noise ratio of photodetectors are needed to meet these demanding ranging applications. Silicon electronics have been the principal option for LiDAR photodetectors in the range of 850–950 nm. However, its indirect bandgap leads to a low absorption coefficient in the near-infrared region, as well as a consequent trade-off between speed and efficiency. Here we report solution-processed lead–tin binary perovskite photodetectors that have an external quantum efficiency of 85% at 850 nm, dark current below 10–8 A cm–2 and response time faster than 100 ps. The devices are fabricated using self-limiting and self-reduced tin precursors that enable perovskite crystallization at the desired stoichiometry and prevent the formation of interfacial defects with the hole transport layer. The approach removes oxygen from the solution, converts Sn4+ to Sn2+ through comproportionation, and leaves neither metallic tin nor SnOx residues. To illustrate the potential of these solution-processed perovskite photodetectors in LiDAR, we show that they can resolve sub-millimetre distances with a typical 50 µm standard deviation.

Enhanced photon harvesting by embedding cost-effective polystyrene microspheres as light scatterers in the perovskite photodetector

Solution processed perovskite photodetectors have attracted extensive interest in recent years.

High-performance perovskite photodetectors based on CH3NH3PbBr3 quantum dot/TiO2 heterojunction

Organo-lead halide perovskite materials have opened up a great opportunity to develop high performance photodetectors because of their superior optoelectronic properties. The main issue with perovskite-only photodetector is severe carrier recombination. Integration of perovskite with high-conductive materials such as graphene or transition metal sulfides certainly improved the photoresponsivity. However, achieving high overall performance remains a challenge. Here, an improved photodetector is constructed by perovskite quantum dots (QDs) and atomic layer deposited ultrathin TiO2 films. The designed CH3NH3PbBr3 QD/TiO2 bilayer device displays inclusive performance with on/off ratio of 6.3 × 102, responsivity of 85 A W−1, and rise/decay time of 0.09/0.11 s. Furthermore, we demonstrate that interface plays a crucial role in determining the device current and enhance the overall performance of heterostructure photodetector through interface engineering. We believe that this work can provide a strategy to accelerate development of high-performance solution-processed perovskite photodetectors.

Ultrasensitive and high gain solution-processed perovskite photodetectors by CH3NH3PbI2.55Br0.45:Zn2SnO4 bulk heterojunction composite

Hybrid perovskite photodetectors, the novel alternative devices transform incident light into electrical signal, have been rapidly developed in the past years. However, intrinsic unbalanced charge carrier transport within hybrid perovskite materials, restricting further boosting device performance of perovskite photodetectors, has rarely been addressed. In this study, we report room temperature–operated solution-processed bulk heterojunction perovskite photodetectors with ultrahigh sensitivity and great photo-gain. It is found that the introduction of Zn2SnO4 nanoparticles into CH3NH3PbI2.55Br0.45 perovskites results in enlarged photocurrent and suppressed dark current for bulk heterojunction perovskite photodetectors. As a result, a responsivity of over 1500 mAW−1 and projected detectivity of approximatively 1014 Jones (1 Jones = cm Hz1/2 W−1) from 380 to 760 nm are observed from bulk heterojunction perovskite photodetectors. In addition, bulk heterojunction perovskite photodetectors exhibit an excellent linear dynamic range of 124 dB and a great photo-gain of 535. All these results indicate that high-performance perovskite photodetectors could be realized through novel bulk heterojunction device structure.

Solution-Processed Ultrahigh Detectivity Photodetectors by Hybrid Perovskite Incorporated with Heterovalent Neodymium Cations.

Hybrid perovskite materials have drawn a remarkable attention for approaching high-performance photovoltaics owing to their superior optoelectronic properties. But most of research studies focused on the pristine hybrid perovskite CH3NH3PbI3. In this study, we utilize a newly developed CH3NH3PbI3:xNd3+ (x = 0.5 mol %) thin film, where Pb2+ is partially substituted by a heterovalent Nd3+ cation, as the photoactive layer for solution-processed perovskite photodetectors. It is found that the resultant CH3NH3PbI3:xNd3+ (x = 0.5 mol %) thin film possesses superior thin film morphology, enhanced and balanced charge carrier mobilities, and suppressed trap density, resulting in enhanced photocurrent and reduced dark current for perovskite photodetectors by the CH3NH3PbI3:xNd3+ (x = 0.5 mol %) thin film. Thus, operated at room temperature, solution-processed perovskite photodetectors exhibit over 1014 cm Hz1/2 W–1 photodetectivity in a spectrum range from 350 to 800 nm, a linear dynamic range over 100 dB, and fast response time. All these results indicate that high-performance solution-processed perovskite photodetectors can be realized by novel hybrid perovskite materials, where Pb2+ is partially substituted by heterovalent Nd3+ cations.