All-perovskite tandem solar cells with dipolar passivation.

Lin, Renxing; Gao, Han; Lou, Jing; Xu, Jian; Yin, Mengran; Wu, Pu; Liu, Chenshuaiyu; Guo, Yijia et al. · Nature · 2025

basic_science · Level V

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Abstract

Non-radiative recombination loss at the hole transport layer (HTL)/perovskite interface in the narrow-bandgap subcell constrains the power conversion efficiency (PCE) of all-perovskite tandem solar cells<sup>1,2</sup>. Minimizing charge recombination at the buried interface of lead-tin (Pb-Sn)-based narrow-bandgap perovskite solar cells has proven to be particularly challenging, as conventional long-chain amine-based passivation strategies often induce carrier transport losses, thereby limiting both the fill factor and the short-circuit current density (J<sub>sc</sub>)<sup>3-5</sup>. Here we developed a dipolar-passivation strategy that reduces the trap density at the buried interface of mixed Pb-Sn perovskite while simultaneously enabling precise energy-level alignment at the HTL/perovskite interface. This dipolar-induced passivation enhances ohmic contact, facilitating efficient hole injection into the HTL and repelling electrons from the HTL/Pb-Sn perovskite interface. This approach extends the carrier diffusion length to 6.2 μm and enables a substantial enhancement in the PCE of Pb-Sn perovskite solar cells, achieving 24.9% along with an open-circuit voltage (V<sub>oc</sub>) of 0.911 V, a J<sub>sc</sub> of 33.1 mA cm<sup>-2</sup> and a high fill factor of 82.6%. Furthermore, the dipolar passivation effectively mitigates contact losses in the narrow-bandgap subcell induced by the interconnecting layer of tandem devices, contributing to an outstanding PCE of 30.6% (certified stabilized 30.1%) in all-perovskite tandem solar cells.