Woo, M.Y.; Im, J.M.; Kim, S.; Youn, P.J.; Jeong, M.J.; Yeom, K.M.; Lee, J.H.; Kim, S.Y.; Kim, D.H.; Yun, Y.; Won, J.H.; Lee, S.; Kim, C.; Kim, D.H.; Han, J.H.; Lee, S.; Noh, J.H.: Purification of Tin Iodide through Solid-State Reaction for Efficient Tin-Lead Mixed Perovskite Solar Cells. Small 21 (2025), p. e11288/1-10
10.1002/smll.202511288
Open Access version by external provider
Abstract:
Tin-lead (Sn-Pb) mixed perovskite solar cells (PSCs), which serve as the rear subcell, have achieved significant advancements, largely driving the remarkable power conversion efficiency (PCE) seen in recent all-perovskite tandem solar cells (TSCs). However, the efficiency of Sn-Pb mixed PSCs is limited by the oxidation susceptibility of Sn2+, which induces the formation of Sn vacancies in the perovskite thin films, leading to an increase in defect densities. To address this issue, a novel approach called metal-assisted solid-state reduction (MASSR) is introduced that effectively purifies tin iodide (SnI2), a critical component in the fabrication of Sn-Pb mixed perovskite thin films. The MASSR process controls the oxidation state of the SnI2, thereby reducing trap densities and minimizing non-radiative recombination losses in the perovskite thin films, which improves the overall efficiency of Sn-Pb mixed PSCs. Consequently, single-junction Sn-Pb mixed PSCs utilizing MASSR-treated SnI2 achieve a high PCE of 22.86%, and their integration with wide-bandgap (WBG) PSCs enables the fabrication of all-perovskite TSCs with a PCE of 26.88%.