Substrate effects on structural and optoelectronic properties of quasi-2D perovskite films

Abstract

Quasi-2D perovskites exhibit broad potential for applications in optoelectronic devices. However, the diverse substrates employed across different application contexts introduce significant challenges to the fabrication of perovskite films. This study methodically investigates the effects of substrates on the crystal structure and optoelectronic properties of quasi-2D perovskite films. By examining films grown on both rigid (glass and single-crystal silicon) and flexible (PEN and PDMS) substrates, we demonstrate the influence of substrates on the crystallographic strain and orientation of perovskite films. These structural changes induce substrate-specific variations in critical parameters, including Urbach energy, exciton binding energy, and electron–phonon coupling, subsequently affecting the optoelectronic performance of the films. Specifically, films on PEN and PDMS substrates show increased photoluminescence (PL) emissions and photoluminescence quantum yields (PLQYs), a consequence of elevated exciton binding energy. Additionally, broadband emissions at room temperature, indicative of pronounced lattice distortions, were notably observed in perovskites on glass and PDMS substrates. The investigation further identifies the enhanced vertical and lateral conductivity of perovskites on PEN substrates, attributable to a reduced trap state density and lower electron–phonon coupling strength. Perovskites on glass substrates promote ion movement due to lower ion activation energy, whereas those on PDMS substrates exhibit reduced conductivity and inhibited ion migration. Our findings highlight the crucial role of substrate selection in fine-tuning the properties of quasi-2D perovskite films, offering invaluable insights for optimizing perovskite-based devices for a wide range of applications.