Permanent Lattice Compression of Lead-Halide Perovskite for Persistently Enhanced Optoelectronic Properties

TL;DR

This study demonstrates a method to induce permanent lattice compression in lead-halide perovskite crystals, resulting in sustained enhanced optoelectronic properties such as increased emission, longer carrier lifetimes, and improved photodetector performance.

Contribution

We introduce an antisolvent-assisted crystallization technique that creates permanent lattice compression in perovskite crystals, leading to persistent optoelectronic enhancements.

Findings

Edges show lattice compression correlating with enhanced emission.

Carrier lifetimes at edges are about 10 times longer than at centers.

Photodetectors with edges exhibit significantly higher detectivity.

Abstract

Under mild mechanical pressure, halide perovskites show enhanced optoelectronic properties. However, these improvements are reversible upon decompression, and permanent enhancements have yet to be realized. Here, we report antisolvent-assisted solvent acidolysis crystallization that enables us to prepare methylammonium lead bromide single crystals showing intense emission at all four edges under ultraviolet light excitation. We study structural variations, edge-vs-center, in these crystals using micro-X-ray diffraction and find that the enhanced emission at the edges correlates with lattice compression compared to in the central areas. Time-resolved photoluminescence measurements show much longer-lived photogenerated carriers at the compressed edges, with radiative component lifetimes of ca. 1.4 us, 10 times longer than at the central regions. The properties of the edges are exploited to fabricate planar photodetectors exhibiting detectivities of 3x10^13 Jones, compared to 5x10^12 Jones at the central regions. The enhanced lifetimes and detectivities correlate to the reduced trap state densities and the formation of shallower traps at the edges due to lattice compression.