ABSTRACT
Metal halide perovskite ferroelectrics possess various physical characteristics such as piezoelectric and pyroelectric effects, which could broaden the application of perovskite ferroelectrics and enhance the optoelectronic performance. Therefore, it is promising to combine multiple effects to optimize the performance of the self-powered PDs. Herein, patterned 2D ferroelectric perovskite (PMA)2PbCl4 microbelt arrays were demonstrated through a PDMS template-assisted antisolvent crystallization method. The perovskite arrays based flexible photodetectors exhibited fine self-powered photodetection performance under 320 nm illumination and much enhanced reproducibility compared with the randomly distributed single-crystal microbelts-based PDs. Furthermore, by introducing the piezo-phototronic effect, the performance of the flexible PD was greatly enhanced. Under an external tensile strain of 0.71%, the responsivity was enhanced by 185% from 84 to 155.5 mA/W. Our findings offer the advancement of comprehensively utilizing various physical characteristics of the ferroelectrics for novel ferroelectric optoelectronics.
Subject(s)
Oxides , Zinc Oxide , Reproducibility of Results , Calcium Compounds , Zinc Oxide/chemistryABSTRACT
The nano-Ag films were prepared by RF magnetron sputtering technique, and all of them were treated by rapid thermal annealing at different temperatures. The structure, the morphology and the optical properties of the annealed nano-Ag films were characterized by X-ray diffraction, scanning electron microscopy, and UV-Vis-NIR spectroscopy. The experimental results show that the open area fraction of the film and spacing between islands or nanoparticles increase with the increase of the annealing temperature, while the aspect ratio decreases. The anisotropic worm-like island films have been reshaped into isotropic nanospheres. The surface plasmon (SP) resonance band blue shifts and narrows continuously with increasing heating temperature. Analyses show that the SP resonance of the nano-Ag films can be modulated by morphology evolution induced by rapid thermal annealing.
ABSTRACT
2D hybrid perovskite ferroelectrics have drawn great attention in the field of photodetection, because the spontaneous polarization-induced built-in electric field can separate electron-hole pairs, and makes self-powered photodetection possible. However, most of the 2D hybrid perovskite-based photodetectors focused on the detection of visible light, and only a few reports realized the self-powered and sensitive ultraviolet (UV) detection using wide bandgap hybrid perovskites. Here, 2D ferroelectric PMA2PbCl4 monocrystalline microbelt (MMB)-based PDs are demonstrated. By using the ferro-pyro-phototronic effect, the self-powered Ag/Bi/2D PMA2PbCl4 MMB/Bi/Ag PDs show a high photoresponsivity up to 9 A/W under 320 nm laser illumination, which is much higher than those of previously reported self-powered UV PDs. Compared with responsivity induced by the photovoltaic effect, the responsivity induced by the ferro-pyro-phototronic effect is 128 times larger. The self-powered PD also shows fast response and recovery speed, with the rise time and fall time of 162 and 226 µs, respectively. More importantly, the 2D PMA2PbCl4 MMB-based PDs with Bi/Ag electrode exhibit significant stability when subjected to high humidity, continuous laser illumination, and thermal conditions. Our findings would shed light on the ferro-pyro-phototronic-effect-based devices, and provide a good method for high-performance UV detection.
ABSTRACT
The Schottky back-contact barrier at the Mo/Cu(In,Ga)Se2 (CIGS) interface is one of the critical issues that restrict the photovoltaic performance of CIGS solar cells. The formation of a MoSe2 intermediate layer can effectively reduce this back-contact barrier leading to efficient hole transport. However, the selenium-free atmosphere is unfavorable for the formation of the desired MoSe2 intermediate layer if the CIGS films are prepared by the commonly used direct sputtering process. In this work, high-efficiency CIGS solar cells with a MoSe2 intermediate layer were fabricated by the direct sputtering process without a selenium atmosphere. This is enabled by an intermediate CIGS layer deposited on the Mo substrate at room temperature before being ramped to a high temperature (600 °C). The room-temperature-deposited amorphous CIGS intermediate layer is Se rich, which reacts with the Mo substrate and forms very thin MoSe2 at the interface during the high-temperature process. The formed MoSe2 decreased the CIGS/Mo barrier height for better hole transport. Consequently, the CIGS solar cell with an 80 nm intermediate layer achieved a power conversion efficiency of up to 15.8%, which is a benchmark efficiency for the direct sputtering process without Se supply. This work provides the industry a new approach for commercialization of directly sputtered CIGS solar cells.