MAPbI3 Quasi-Single-Crystal Films Composed of Large-Sized Grains with Deep Boundary Fusion for Sensitive Vis-NIR Photodetectors.

Perovskite single-crystal (SC) or quasi-single-crystal (QSC) films are promising candidates for excellent performance of photoelectric devices. However, it is still a great challenge to fabricate large-area continuous SC or QSC films with proper thickness. Herein, we propose a pressure-assisted high-temperature solvent-engineer (PTS) strategy to grow large-area continuous MAPbI3 QSC films with uniformly thin thickness and orientation. Dramatic grain growth (∼100 μm in the lateral dimension) and adequate boundary fusion are realized in them, vastly eliminating the grain boundaries. Thus, remarkable diminution of the trap density (ntrap: 7.43 × 1011 cm-3) determines a long carrier lifetime (τ2: 1.7 μs) and superior photoelectric performance of MAPbI3-based lateral photodetectors; for instance, an ultrahigh on/off ratio (>2.4 × 106, 2 V), great stability, fast response (283/306 μs), and high detectivity (1.41 × 1013) are achieved. The combination properties and performance of the QSC films surpass most of the reported MAPbI3. This effective approach in growing perovskite QSC films points out a novel way for perovskite-based optoelectronic devices with superior performance.