Low Temperature Synthesis of Stable γ‐CsPbI₃ Perovskite Layers for Solar Cells Obtained by High Throughput Experimentation

Abstract

The structural phases and optoelectronic properties of coevaporated CsPbI3 thin films with a wide range of [CsI]/[PbI2] compositional ratios are investigated using high throughput experimentation and gradient samples. It is found that for CsI‐rich growth conditions, CsPbI3 can be synthesized directly at low temperature into the distorted perovskite γ‐CsPbI3 phase without detectable secondary phases. In contrast, PbI2‐rich growth conditions are found to lead to the non‐perovskite δ‐phase. Photoluminescence spectroscopy and optical‐pump THz‐probe mapping show carrier lifetimes larger than 75 ns and charge carrier (sum) mobilities larger than 60 cm2 V−1 s−1 for the γ‐phase, indicating their suitability for high efficiency solar cells. The dependence of the carrier mobilities and luminescence peak energy on the Cs‐content in the films indicates the presence of Schottky defect pairs, which may cause the stabilization of the γ‐phase. Building on these results, p–i–n type solar cells with a maximum efficiency exceeding 12% and high shelf stability of more than 1200 h are demonstrated, which in the future could still be significantly improved, judging on their bulk optoelectronic properties.

Inorganic Halide Perovskite Solar Cells: Progress and Challenges

“…CsPbI 3 typically exhibits a yellow nonperovskite phase at room temperature and a black cubic perovskite phase with a bandgap of 1.73 eV that is stable at high temperatures but very unstable at room temperature. [ 130 ] The first CsPbI 3 PSC was reported by Choi et al in 2014. [ 52 ] They attempted to remove MA + from Cs x MA 1− x PbI 3 solar cells, resulting in a low PCE of only 0.09%.…”

Ion Migration: A “Double‐Edged Sword” for Halide‐Perovskite‐Based Electronic Devices

“…Recently, inorganic perovskite materials such as CsPbI 3 , CsPbI 2 Br, and CsPb x Sn 1− x I 3 have been widely explored for solar cells, LEDs, photodetectors, and RS memory devices . Compared with HOIPs, the thermal stability of inorganic perovskite materials is greatly improved, greatly advantage toward real applications.…”

“…As shown in Table 3 , the hysteresis effect was also observed in most inorganic perovskite‐based PVSCs regardless of device structure . In addition, the hysteresis even exists in lead‐free PVSCs using CsSnI 3 , Cs 2 SnI 6 as light absorber .…”

Computational high throughput screening of inorganic cation based halide perovskites for perovskite only tandem solar cells

“…However, the degree of stability varies with the variation of the 3 inorganic cations using in this study. From the experimental point of view, as mentioned in literature [51,52], Cs-based halide perovskites are expected to exist in 4 phases: the cubic (∝), the tetragonal (β), and 2 orthorhombic phases (black γ and a nonperovskite yellow δ phase). The cubic (∝) phase is stable at high temperature (>578 K).…”