Key issues and solutions affecting efficiency and stability of perovskite/heterojunction tandem solar cells

Efficient and stable perovskite/heterojunction tandem solar cells (PTSC) are a direction of joint exploration in both academia and industry. Achieving efficient solar energy utilization by assembling structural layers with different bandgaps in an optical sequence is the original design strategy for PTSC. Through the reasonable distribution of the absorption spectra of each layer, the photoelectric conversion efficiency (PCE) of PTSC can theoretically be increased to more than 40%. At present, the efficiency advantage of small-area PTSC is well-established, but there are still many challenges in the commercialization of solar cell efficiency and stability. Therefore, in this work, the two-terminal (2T) and four-terminal (4T) stacking methods are regarded as the main structural routes, and the optimal design of the key structural layers of PTSC, bandgap adjustment, additive regulation, optimization of interlayer transport, and optimization of the module interconnection and encapsulation methods are focused on. Based on the existing research results, the key problems and solutions affecting the efficiency and stability of PTSC are summarized and outlooked, aiming to provide directional solutions to the key problems in the structural design of PTSC. In addition, from the application perspective, it is proposed that before the stability problem of the perovskite is fundamentally solved, the 4T PTSC is more likely to achieve product iteration and industrial efficiency improvement, with the expectation of taking the lead in commercialization. This work emphasizes the popularization and practical application of commercialization, with a perspective that is more in line with the market trend and close to the industrial demand, and is expected to provide an important reference for the commercialization of PTSC in the academic circles.