Ecofriendly Mn<sub>3</sub>O<sub>4</sub> as a Novel Hole Transport Material for Efficient and Ultrastable Flexible and Rigid Perovskite Solar Cells
Zijun Yi, Wang Li, Bo Xiao, Wenguang Zhang, Yuchen Xiong, Yubo Luo, Qinghui Jiang, Xin Li, Junyou Yang
Abstract
Exploring ecofriendly, low-cost, and chemically stable hole transport materials (HTMs) is of great significance for the commercial application of perovskite solar cells (PSCs). In view of this, we first employed the inorganic p-type semiconductor trimanganese tetraoxide (Mn 3 O 4 ) as a HTM prepared by vacuum vapor deposition for flexible and rigid PSCs. It was revealed that the Mn 3 O 4 material presented a suitable band structure, outstanding electrical conductivity, and hole mobility, which was a potential HTM for PSCs. The optimized flexible and rigid PSCs based on the Mn 3 O 4 thickness (50 nm) achieved the best photoelectric conversion efficiencies (PCEs) of 15.58 and 18.07%, respectively. More importantly, the unencapsulated rigid device based on Mn 3 O 4 exhibited outstanding stability and retained 91.7% of the original PCE after storage for 1000 h at double 85 condition (85 °C and 85 ± 5% relative humidity). Additionally, the target flexible PSCs still maintained 92.3% of the initial efficiency after 1000 bending cycles with a radius of 5 mm. Obviously, the Mn 3 O 4 semiconductor is a promising candidate as a HTM compatible with flexible and rigid PSCs, which plays a pivotal role in improving the stability of the devices. It is believed that our research results provide new insights for realizing cost-effective and ultrastable photovoltaic devices.