Tailoring Photoluminescence by Strain-Engineering in Layered Perovskite Flakes

TL;DR

This study demonstrates that applying strain to layered hybrid organic-inorganic perovskite flakes significantly alters their photoluminescence, enabling tunable optoelectronic properties for potential sensing and device applications.

Contribution

It provides the first detailed investigation of strain effects on PL in 2D HOIPs, revealing how mechanical deformation modulates bandgap and emission characteristics.

Findings

<1% strain changes PL from single to multiple peaks

Strain modulates bandgap via octahedral tilting and lattice expansion

Coexistence of tensile and compressive strain observed

Abstract

Strain is an effective strategy to modulate the optoelectronic properties of 2D materials, but it has been almost unexplored in layered hybrid organic-inorganic metal halide perovskites (HOIPs) due to their complex band structure and mechanical properties. Here, we investigate the temperature-dependent microphotoluminescence (PL) of 2D $(C_6H_5CH_2CH_2NH_3)_2Cs_3Pb_4Br_{13}$ HOIP subject to biaxial strain induced by a $SiO_2$ ring platform on which flakes are placed by viscoelastic stamping. At 80 K, we found that a strain of <1% can change the PL emission from a single peak (unstrained) to three well-resolved peaks. Supported by micro-Raman spectroscopy, we show that the thermomechanically generated strain modulates the bandgap due to changes in the octahedral tilting and lattice expansion. Mechanical simulations demonstrate the coexistence of tensile and compressive strain along the flake. The observed PL peaks add an interesting feature to the rich phenomenology of photoluminescence in 2D HOIPs, which can be exploited in tailored sensing and optoelectronic devices.