Science News: 2021 Advanced Materials Achieve 24.4% PCE! Interface Material-Introduction of Biguanide Hydrochloride (BGCl)

　　Advanced Materials (IF 30.849) published a study in December 2021. Interfacial modification that serves multiple roles is very important for manufacturing efficient and stable perovskite solar cells. Here, the authors propose an interface material that introduces a multi-functional interfacial material, biguanide hydrochloride (BGCl), between SnO₂ and perovskite to enhance electron extraction and crystal growth of perovskite. The BGCl can chemically connected to the SnO₂ through Lewis coordination/electrostatic coupling and helps to anchor PbI₂.

　　The research team used a solar simulator to analyze its photovoltaic characteristics and used other instruments to assist in the experiments. It is found that through this method, better energy alignment, reduced interfacial defects and homogeneous perovskite crystallites are achieved. Its power conversion efficiency (PCE) comes to 24.4%, with an open circuit voltage of 1.19 V and a drastically improved fill factor of 82.4%. The important thing is that the unencapsulated device can still maintain 95% of its initial PCE after aging for over 500 h at 20°C and 30% relative humidity in ambient conditions. These results show that the incorporation of BGCI can modify the interface and control the crystallization of the perovskite, thereby realizing efficient and stable perovskite solar cells and other perovskite-based electronics, which is a promising strategy.