Solvent-Assisted Thermal-Pressure Strategy for Constructing High-Quality CH3NH3PbI3- xCl x Films as High-Performance Perovskite Photodetectors

High-quality CH₃NH₃PbI_3-xCl _x films have attracted research interests in photoelectric devices because of their improved carrier diffusion length and charge mobility. Herein, a solvent-assisted thermal-pressure strategy is developed to promote the secondary growth of perovskite grains in the films. Highly oriented perovskite films are then obtained with large-sized grains (5-10 μm). As a consequence, the photodetectors based on the high-quality CH₃NH₃PbI_{3- x}Cl _x films exhibit enhanced ophtoelectrical performance, including high on/off ratio (>2.1 × 10⁴), fast response time (54/63 μs), and high detectivity (∼1.3 × 10¹²). This work suggests an effective approach for high-quality perovskite films, which will be promising candidates for other high-efficiency photoelectric devices.

Sequentially Vapor-Grown Hybrid Perovskite for Planar Heterojunction Solar Cells

High-quality and reproducible perovskite layer fabrication routes are essential for the implementation of efficient planar solar cells. Here, we introduce a sequential vapor-processing route based on physical vacuum evaporation of a PbCl₂ layer followed by chemical reaction with methyl-ammonium iodide vapor. The demonstrated vapor-grown perovskite layers show compact, pinhole-free, and uniform microstructure with the average grain size of ~ 320 nm. Planar heterojunction perovskite solar cells are fabricated using TiO₂ and spiro-OMeTAD charge transporting layers in regular n-i-p form. The devices exhibit the best efficiency of 11.5% with small deviation indicating the high uniformity and reproducibility of the perovskite layers formed by this route.

Effects of precursor solution composition on the performance and I-V hysteresis of perovskite solar cells based on CH3NH3PbI3-xClx

Precursor solution of CH₃NH₃PbI_3-xCl_x for perovskite solar cells was conventionally prepared by mixing PbCl₂ and CH₃NH₃I with a mole ratio of 1:3 (PbCl₂:CH₃NH₃I). While in the present study, CH₃NH₃PbI_3-xCl_x-based solar cells were fabricated using the precursor solutions containing PbCl₂ and CH₃NH₃I with the mole ratios of 1:3, 1.05:3, 1.1:3, and 1.15:3, respectively. The results display that the solar cells with the mole ratio of 1.1:3 present higher power conversion efficiency and less I-V hysteresis than those with the mole ratio of 1:3. Based on some investigations, it is concluded that the higher efficiency could be due to the smooth and pinhole free film formation, high optical absorption, suitable energy band gap, and the large electron transfer efficiency, and the less I-V hysteresis may be attributed to the small low frequency capacitance of the device.