Strain-Induced Modification of Photoluminescence in Quasi-2D Perovskite Thin Films

Abstract

Quasi-2D perovskites are recognized as a promising material for lightweight photovoltaic applications. For these applications, it is critical to understand how mechanical stresses affect the perovskite’s optoelectronic properties. Here, we discuss how applied stress impacts the photoluminescence spectrum and lifetime of quasi-2D perovskite thin films and how these effects depend on interlayer cation choice (butylammonium or phenethylammonium) and film processing (hot-casting versus postdeposition annealing). We find that compressive stress induces an enhancement and spectral redshift (>10 meV per percent strain) in the emission from bulk-like grains in the film. Moreover, the charge carrier recombination lifetime is greatly enhanced (up to a factor of 14 with only 1% strain). We show that the phenethylammonium-based perovskites are more robust against strain-induced modifications compared to those containing the butylammonium cation. These results highlight how strongly strain can modify the optoelectronic properties of quasi-2D perovskite thin films and how cation choice and film processing can have important practical implications for developing lightweight photovoltaics.