Achieving highly ordered and uniformly covered self-assembly monolayers (SAMs) with optimal packing configuration on textured silicon substrates remains a critical challenge for further improving the efficiency of perovskite/silicon tandem solar cells (TSCs)1-3. Here we design an asymmetric SAM (named as HTL201) featuring anchoring group and spacer flanking a carbazole core, serving as hole selective layer (HSL) for perovskite/silicon TSCs. When compared to symmetric SAMs with nitrogen-bonded phosphonic acid group, the HTL201 molecule exhibits minimized steric hindrance and improved coverage on the transparent conductive oxide (TCO) recombination layer. The strong coordination interaction between HTL201 and perovskite film effectively reduces non-radiative recombination at buried interface. Notably, the optimized energy level alignment between perovskite and HTL201, accompanied by an increase in quasi-Fermi level splitting (QFLS) value of the perovskite layer, enables an impressive voltage of nearly 2 V for perovskite/silicon TSCs, resulting in a certified power conversion efficiency (PCE) of up to 34.58% based on a silicon heterojunction (SHJ) solar cell.
© 2025. The Author(s), under exclusive licence to Springer Nature Limited.