Suppression of Phase Transitions in Perovskite Thin Films through Cryogenic Electron Beam Irradiation

Abstract

Organic–inorganic hybrid perovskites (OIHPs) with superior optoelectronic properties have emerged as revolutionary semiconductor materials for diverse applications. A fundamental understanding of the interplay between the microscopic molecular-level structure and the macroscopic optoelectronic properties is essential to boost device performance toward theoretical limits. Here, we reveal the critical role of CH3NH3 + (MA) in the regulation of the physicochemical and optoelectronic properties of a MAPbI3 film irradiated by an electron beam at 130 K. The order-to-disorder transformation of the MA cation not only leads to a notably enhanced photoluminescence emission but also results in the suppression of the orthorhombic phase down to 85 K. Taking advantage of the regulation of MA cation dynamics, we demonstrate a perovskite photodetector with 100% photocurrent enhancement and long-term stability exceeding one month. Our study provides a powerful tool for regulating the optoelectronic properties and stabilities of perovskites and highlights potential opportunities related to the organic cation in OIHPs.

Low-temperature photoluminescence measurement with a micromachined Joule-Thomson cooler

“…In the temperature range of 165-175 K, the sample exhibited a single peak, indicating complete transition from the orthogonal phase to the tetragonal phase. These results align with Jin et al's research [7] and strongly validate the efficacy of the MJT cooling method for the PL sample. Finally, we conducted a test to evaluate the impact of vacuum on preserving the PL performance.…”

“…PL testing was conducted within the temperature range of 115-175 K, which covers the orthorhombic phase-change point of the sample. This temperature range is expected to result in a significant change in the PL spectra, allowing for verification with existing literature [7].…”

“…The PL sample utilized in this study is a thin film of MAPbI3, a type of halide lead perovskite. It is chosen because of its clear PL mechanism and wide range of applications [7]. A silicon chip is attached to the cold end of the cooler using silver glue.…”

Cryogenic Electron-Beam Writing for Perovskite Metasurface

“…However, long cracks on the perovskite can be clearly observed in SEM images (Figure S3), which were caused by chilling shrinkage and room-temperature e-beam irradiation for imaging. 35 In the following content, we focus on exposed solid anisole metasurfaces consisting of identical nanopillars. Influences of structure parameters on the optical absorption of the metasurface have been investigated by finite-difference timedomain (FDTD) simulation (Figure S4).…”

“…Thanks to fine protection of solid anisole ice coverage, we did not see obvious destruction including small particles, surface roughening, and pinholes to the perovskite surface after e-beam patterning (Figure S2). However, long cracks on the perovskite can be clearly observed in SEM images (Figure S3), which were caused by chilling shrinkage and room-temperature e-beam irradiation for imaging …”