Researchers from LONGi Green Energy Technology, the Hong Kong Polytechnic University (PolyU), Soochow University, Beijing University of Technology, Chinese Academy of Sciences and the University of Science and Technology of China have tackled the challenge of achieving ordered and uniformly covered self-assembly monolayers (SAMs) with optimal packing configuration on textured silicon substrates, for improving the efficiency of perovskite/silicon tandem solar cells.
The team designed an asymmetric SAM (named as HTL201), featuring anchoring group and spacer flanking a carbazole core, serving as hole selective layer (HSL) for perovskite/silicon tandem solar cells. When compared to symmetric SAMs with nitrogen-bonded phosphonic acid group, the HTL201 molecule reportedly exhibited minimized steric hindrance and improved coverage on the transparent conductive oxide (TCO) recombination layer.
The strong coordination interaction between HTL201 and perovskite film is said to effectively reduce 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 tandem solar cells, resulting in a certified power conversion efficiency (PCE) of up to 34.58% based on a silicon heterojunction (SHJ) solar cell.
