A Helical Polycycle Molecular Semiconductor for Durable and Efficient Perovskite Solar Cells

Despite the efficiency comparable to crystalline silicon photovoltaics, it is still a severe concern on the long-term stability under the stress of heat, light, and bias potential for perovskite solar cell (PSC). Here, we report a triple aza[6]helicene-based molecular semiconductor (TBTA[6]H) characteristic of a fully fused conjugated backbone. TBTA[6]H presents superior solubility and glass-transition temperature (T-g). An air-doped composite of TBTA[6]H with a high electrical conductivity of 353 mu S cm(-1) is still featured by a T-g of 112 degrees C, enabling the fabrication of 22% efficiency, 85 degrees C durable PSCs. The TBTA[6]H composite not only exhibits an excellent morphology stability at 85 degrees C in PSCs, but also remarkably attenuates the thermal degradation of photoactive perovskite layer. The cell with TBTA[6]H also displays an excellent operation stability under the continuous full sunlight soaking at 55 degrees C.