Dopant-free carrier-selective contact silicon solar cells: Materials, structures and stability

Crystalline silicon solar cells capture over 95 % of the photovoltaic market, supported by a well-established industrially framework. Key determinants for their practical deployment include increased photovoltaic conversion efficiency, reduced production costs, and improved stability. However, the efficiency enhancement is limited by parasitic absorption, a consequence of doped silicon layers. In response, dopant-free carrier selective contact silicon solar cells have emerged as a focal point of interest, offering benefits such as sub-200 degrees C processing temperatures, ease of material control, and superior field passivation. The utilization of wide-bandgap carrier-selective materials in silicon-based solar cells represents a burgeoning area, showcasing significant po- tential to approach the theoretical efficiency for solar cells. Nevertheless, the challenges are persisting in terms of controlling carrier concentration and work function, constructing high-efficiency devices, and ensuring envi- ronmental stability. These challenges continue to impede progress in this field. This article initially presents the operational principles and the current advancement status of dopant-free silicon solar cells, subsequently delving into the latest developments in their structural design and research. It further discusses the challenges and op- portunities for further study, highlighting the breakthroughs required for the realisation of high-efficiency, high- stability solar cells and dual-sided power generation technology.