Highly Efficient and Stable Perovskite Solar Cells Enabled by All-Crosslinked Charge-Transporting Layers

Despite the demonstrated high power conversion efficiency (PCE) of perovskite solar cells (PVSC), long-term stability of the device operated in humid environments under photo- and thermal stresses is still a serious concern prior to any commercialization. To provide possible solutions to overcome this hurdle, we have synthesized an n-type conjugated molecule, c-HATNA, that can be crosslinked as an electron-transporting layer (ETL) on top of the desired perovskites. By proper doping to increase its electron-transporting property, a high PCE of 18.21% can be obtained with respectable moisture and thermal stability without encapsulation. Moreover, this c-HATNA ETL can be used in conjunction with another crosslinkable hole-transporting layer, c-TCTA-BVP, to fabricate all-crosslinked charge-transporting layers (CTLs) for PVSCs and achieve 16.08% and 13.42% PCEs on rigid and flexible substrates, respectively. More importantly, the device with all-crosslinked CTLs showed impressive thermal stability in ambient environment: almost 70% of its initial PCE after being heated at 70°C for 300 hr.