The Stabilization of CsPbI_3−xBr_x Phase by Lowering Annealing Temperature for Efficient All‐Inorganic Perovskite Solar Cells

Abstract

All‐inorganic perovskites are a promising solution for the fabrication of thermally stable perovskite solar cells (PSCs) with remarkable performances. However, a high annealing temperature is required for the stabilization of the photoactive phase of CsPbI3, which represents a limiting factor for their potential scaling‐up and manufacturing at industrial scale. This work demonstrates a new process for the stabilization of CsPbI3‐xBrx perovskite at lower annealing temperature of 180°, based on a rational halogen substitution enabled by the introduction of dimethylammonium (DMA) additives. Bromide inclusion favors indeed the conversion from the intermediate phases to CsPbI3‐xBrx. Standard mesoscopic solar cells prepared with this approach achieve a power conversion efficiency (PCE) of 14.86%, with reduced voltage losses and increased fill factor (FF) compared to the reference device. Moreover, this work proves that a rational substitution of the halide in the DMA salt is also beneficial for the devices annealed at higher temperature, achieving an encouraging PCE of 16.23%. By reducing the processing temperature, this new method widens the range of applications of all‐inorganic PSCs toward temperature‐sensitive materials and industrial applications.This article is protected by copyright. All rights reserved.

All‐Inorganic Perovskite Solar Cells: Modification Strategies and Challenges

“…Reprinted with permission. [68] Copyright 2023, Wiley-VCH GmbH. f ) Evolution of the crystal structure and space group of CsPbBr 3 single crystal with the InCl 3 dopant.…”

“…Moreover, Montecucco and his team identified that DMAX (dimethylammonium xanthate) can also be employed to finetune the crystallization process of all-inorganic perovskite by lowering the annealing temperature, showcasing the versatility and effectiveness of this approach in diverse contexts (Figure 3e). [68] Mai et al showed that the introduction of the inorganic indium chloride ion (InCl 3 ) dopant into the lattice structure of inorganic CsPbI 2 Br can also help to inhibit the formation of the yellow phase (Figure 3f ). [69] This modification enables AIWPSCs to maintain their efficiency for up to 80 h in ambient air without any degradation.…”