Affiliation:
1. Key Laboratory of Optical Field Manipulation of Zhejiang Province Department of Physics Zhejiang Sci‐Tech University Hangzhou 310018 China
2. State Key Laboratory of Silicon and Advanced Semiconductor Materials & School of Materials Science and Engineering Zhejiang University Hangzhou 310027 China
Abstract
AbstractCarrier‐selective passivating contacts using transition metal oxides (TMOs) have attracted great attention for crystalline silicon (c‐Si) heterojunction solar cells recently. Among them, tantalum oxide (Ta2O5) exhibits outstanding advantages, such as a wide bandgap, good surface passivation, and a small conduction band offset with c‐Si, which is typically used as an electron‐selective contact layer. Interestingly, it is first demonstrated that solution‐processed Ta2O5 films exhibit a high hole selectivity, which blocks electrons and promotes hole transport simultaneously. Through the ozone pre‐treatment of Ta2O5/p‐Si interface and optimization of the film thickness (≈9 nm), the interfacial recombination is suppressed and the contact resistivity is reduced from 178.0 to 29.3 mΩ cm2. Moreover, the Sn4+ doping increases both the work function and oxygen vacancies of the film, contributing to the improved hole‐selective contact performance. As a result, the photoelectric conversion efficiencies of Ta2O5/p‐Si heterojunction solar cells are significantly improved from 14.84% to 18.47%, with a high thermal stability up to 300 °C. The work has provided a feasible strategy to explore new features of TMOs for carrier‐selective contact applications, that is, bipolar carrier transport properties.
Funder
National Natural Science Foundation of China
Natural Science Foundation of Zhejiang Province
Subject
Biomaterials,Biotechnology,General Materials Science,General Chemistry