Tin-based perovskite solar cells (TPSCs) offer several advantages, including low toxicity and a near-ideal bandgap. However, their full potential has yet to be realized due to key challenges. To tackle these obstacles, researchers from Changzhou University and Yangzhou University in China focused on two primary issues hindering the performance of Sn-based perovskite solar cells: uncontrolled crystallization and the rapid oxidation of Sn²⁺ within the perovskite layer.
The team developed a strategy to improve the performance of TPSCs by incorporating an additive with multiple functional groups, S-benzylisothiourea hydrochloride (SBT), into the Sn-based perovskites. SBT can form strong interactions with the Sn-based perovskite by coordinating with Sn2+ and I−, and thus restrains the oxidation from Sn2+ to Sn4+ effectively and slows down the perovskite crystallization process.
As a result, compact and smooth Sn-based perovskite films with decreased defect state density, suppressed unfavorable p-type doping, and enhanced 2D/3D perovskite phase are obtained.
The champion TPSC achieved a power conversion efficiency (PCE), a fill factor, a short-circuit current density, and an open-circuit voltage of 9.56%, 73.09%, 21.06 mA cm−2, and 0.62 V, respectively.
Notably, the devices without encapsulation demonstrated good stability in nitrogen atmosphere, maintaining 93.0% of their initial PCE over 1500 h at room temperature and 86.2% of their initial PCE over 16 h at 85 °C.
This work provides a novel additive to improve the performance of TPSCs, which is a valuable attempt to develop multifunctional additives for control of crystallization and Sn2+ oxidation in TPSCs.
