High-Quality CH3NH3PbI3 Films Obtained via a Pressure-Assisted Space-Confined Solvent-Engineering Strategy for Ultrasensitive Photodetectors

High-quality organic–inorganic hybrid perovskite films are crucial for excellent performance of photoelectric devices. Herein, we demonstrate a pressure-assisted space-confined solvent-engineering strategy to grow highly oriented, pinhole-free thin films of CH 3 NH 3 PbI 3 with large-scale crystalline grains, high smoothness, and crystalline fusion on grain boundaries. These single-crystalline grains vertically span the entire film thickness. Such a film feature dramatically reduces recombination loss and then improves the transport property of charge carriers in the films. Consequently, the photodetector devices, based on the high-quality CH 3 NH 3 PbI 3 films, exhibit high photocurrent (105 μA under 671 nm laser with a power density of 20.6 mW/cm 2 at 10 V), good stability, and, especially, an ultrahigh on/off ratio ( I light /I dark > 2.2 × 10 4 under an incident light of 20.6 mW/cm 2 ). These excellent performances indicate that the high-quality films will be potential candidates in other CH 3 NH 3 PbI 3 -based photoelectric devices.