The energy conversion efficiency of two-terminal perovskite/silicon tandem solar cells far surpasses that of single-junction solar cells, bringing a revolutionary breakthrough to the photovoltaic field. However, the failure to effectively optimize device interfaces, maximize charge extraction efficiency, and reduce energy losses has limited their potential for widespread application.
A research team from The Hong Kong Polytechnic University (PolyU) has proposed an innovative double-layer interface passivation strategy, successfully boosting the conversion efficiency of perovskite/silicon tandem solar cells to a record-high 33.89%, marking a new milestone in the development of solar technology.
For a long time, the carrier recombination issue at the interface between perovskite and the electron transport layer has severely restricted the efficiency improvement of perovskite/silicon tandem solar cells. Led by Professor Yin Jun, Assistant Professor in the Department of Applied Physics at PolyU, the research team combined advanced material design and device optimization strategies to develop highly efficient perovskite/silicon tandem solar cells, achieving a significant breakthrough in interface engineering.
This research, conducted in collaboration with LONGi Green Energy Technology Co., Ltd. and Soochow University, has been published in the international journal Nature.
The team innovatively combined the deposition of a nanoscale ultrathin lithium fluoride (LiF) layer and ethylenediamine iodide (EDAI) molecules to achieve simultaneous field and chemical passivation, forming a double-layer interwoven passivation structure. This helps maintain efficient electron extraction and suppress non-radiative recombination.
The team then combined the perovskite material employing this strategy with a double-textured silicon heterojunction cell featuring a gently textured front surface and a highly textured rear surface, successfully constructing a high-performance perovskite/silicon tandem solar device. This device enhances light current capture capability while maintaining the passivation effect on the cell’s rear side, achieving synergistic optimization of light absorption and charge transport.
The perovskite/silicon tandem solar cells fabricated using this double-layer interface passivation strategy have been certified by independent institutions, demonstrating an energy conversion efficiency of up to 33.89%, surpassing for the first time the Shockley-Queisser limit’s proposed maximum energy conversion rate for single-junction solar cells (33.7%). Additionally, the cells exhibit other outstanding photovoltaic performances, including a fill factor of up to 83%, an open-circuit voltage close to 1.97 V, and significantly improved long-term stability.
