High-efficiency perovskite photovoltaic modules achieved via cesium doping

Abstract

By using the Cs-doped MAPbI 3 as the model perovskite materials, several effects arising from the doping of Cs + into hybrid perovskites have been summarized. Significantly, a suppression of ion migration effects and an improvement in the diffusion length were observed. The Cs + doped PSCs showed hysteresis-free behavior, device efficiency boosted from 19.73% to 21.72%, and the fabricated modules (6.5 cm × 7 cm) with a high PCE of 21.08% via “non-destructive replicate” of all photovoltaic parameters from small device. • Cs-doped MAPbI 3 acts as the model perovskite materials. • Doping of Cs + into hybrid perovskites significantly suppresses ion migration. • Cs + doping noticeably increases the carrier diffusion length of the perovskite film. • The Cs + doped PSCs showed hysteresis-free behavior. • Fabricated cell efficiency reached 21.72%, and module over 21.08% Perovskite solar modules have been attracting increasing attention due to their market potential, yet publications concerned with theintrinsic scale-up potential of different perovskite compositions remain relatively scarce. On the other hand, while great success is being made towards improving the power conversion efficiency ( PCE ) of perovskite solar cells (PSCs) by cesium cation (Cs + ) doping of the perovskite, more attention is being paid to the perovskite phase stabilization effect of Cs + doping, and less to other properties that are critical to understand and futher improve the PSC’s. In this work, moderately-Cs-doped MAPbI 3 was employed as a model perovskite material in order to exclude the phase stabilization effect. Our systematic study revealed the influence of Cs + in organic–inorganic hybrid perovskites on the crystal structure, crystallization process, trap state density, band structure and charge (i.e. , ions or photo-carriers) transport. Markedly, it has been observed that Cs + doping can greatly increase the carrier diffusion length in the perovskite films, thus improving the potential to scale-up PSC’s.The PCE of small area devices (0.09 cm 2 ) was increased to 21.72% from 19.73%, with decreased hysteresis behavior and increased operational stability (T 85 = 1000 h) after Cs + doped, where T 85 refers to the retention of 85% of the initial PCE . Moreover, a PCE of 21.08% was obtained for a Cs + -containing perovskite module with an active area > 30 cm 2 , which demonstrates a better “reproducibility” than the reference sample (MAPbI 3 -based perovskite modules, PCE = 18.26%).