Indium Iodide Additive Realizing Efficient Mixed Sn─Pb Perovskite Solar Cells

The commonly used hole transport layer (HTL) Poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) still has some shortcomings that will limit the development of Pb–Sn perovskite solar cells (PSCs). In this work, multifunctional ammonium sulfide (AS) is attempted to modify PEDOT:PSS/perovskite interface. AS has multiple effects on different functional layers and the device as a whole: a) optimize the perovskite crystallization by the formation of PbS nucleation sites; b) neutralize the acidity of PEDOT:PSS by reaction with PSS; c) promote carrier transport at HTL/perovskite interface by tuning the energy level of PEDOT:PSS. As a result, a power conversion efficiency of 24.23% is obtained in the reverse scanning direction and 23.84% in the steady‐state output power test for the single‐junction Pb–Sn PSCs, and 27.48% for all‐perovskite tandem solar cells. These results show that AS modification can be an effective way to boost the development of Pb–Sn PSCs.

Multifunctional Ammonium Sulfide Enables Highest Efficiency Lead–Tin Perovskite Solar Cells

Song,

Kong,

Zhao

et al. 2024

Inhibiting Ion Migration and Oxidation in Sn–Pb Perovskite by Multidentate Chelating Additive Strategy

Ma,

Zhao,

Yang

et al. 2024

Currently, all‐perovskite tandem solar cells have achieved power conversion efficiencies exceeding 29%. The further improvement is limited by mixed Sn–Pb narrow‐bandgap perovskite subcells. The facile oxidation of Sn2+ to Sn4+ poses an inherent challenge that limits the efficiency and stability of Sn–Pb perovskite solar cells. In this study, a multi‐dentate chelating additive, 3‐amino‐2‐chloroisonicotinamide (ACPC), is developed. Its amino group could anchor I− of the perovskite lattice by hydrogen bonds, thereby preventing I− migration and oxidation. On the other hand, the carbonyl group of ACPC as a Lewis base group could coordinate with Sn2+, effectively protecting Sn2+ from oxidation. Ultimately, the multi‐dentate chelating effect of ACPC helps to suppress the oxidation of Sn–Pb perovskite and its related nonradiative recombination. The resulting Sn–Pb perovskite solar cells obtain a top power‐conversion efficiency (PCE) of 23.09% and a high open‐circuit voltage (VOC) of 0.902 V while the control values only reach 19.11% and 0.825 V. As a result of the improved performance of the Sn–Pb perovskite solar cells, the corresponding all‐perovskite tandem solar cells achieve a PCE of 27.60%, retaining 85.7% of initial PCE after 500 h continuous 1 sun illumination.

Synergistic Treatments of Bulk and Surface in Tin‐Lead Mixed Perovskite for Efficient All‐Perovskite Tandem Solar Cells

Xie,

Jin,

Cao

et al. 2024

Narrow‐bandgap (NBG) perovskites have attracted significant attention for their promising potential as light‐absorbing materials in tandem solar cells. However, tin‐lead mixed perovskites face a major limitation of the facile oxidation of Sn2⁺, leading to Sn vacancies in the perovskite films. In this study, sodium triacetoxyborohydride (STAB) is introduced as an antioxidant, while potassium (5‐bromo‐2‐fluoropyridin‐3‐yl)trifluoroborate (PBFT) is employed as a surface modifier for mixed tin‐lead perovskites. This combined approach not only suppresses Sn2⁺ oxidation but also promotes the formation of high‐quality perovskite films. Furthermore, the induced energy band bending at the perovskite/C60 interface substantially enhances charge transfer. Consequently, the optimized device achieves a power conversion efficiency (PCE) of 23.41% with excellent illumination stability. When paired with a wide‐bandgap (WBG) semi‐transparent perovskite solar cell (PSC), the resulting four‐terminal (4‐T) all‐perovskite tandem solar cell attains a remarkable efficiency of 27.37%.