Cost-Effective High-Performance Charge-Carrier-Transport-Layer-Free Perovskite Solar Cells Achieved by Suppressing Ion Migration

Perovskite solar cells (PSCs) without charge-carrier-transport layers (CTLs) are theoretically achievable due to the ambipolar charge-carrier-transfer characteristics presenting in perovskites. However, the power conversion efficiency (PCE) of the CTL-free PSCs needs further improvement. Herein, we provide a breakthrough in the fabrication of the cost-effective high-performance hole-transport-layer (HTL)-free PSC and trilayer PSC with device configurations of fluorine doped tin oxide (FTO)/SnO2/perovskite/carbon and FTO/perovskite/carbon, respectively. We introduce perfluorotetradecanoic acid (PFTeDA) with a carbonyl unit and carbon fluorine bonds to suppress the ion migration and reduce the crystal defects in perovskites. The modified carbon-based HTL-free PSC shows a record PCE of 18.9%. Furthermore, the PFTeDA molecules are found existing at the grain boundaries between the perovskite crystals, resulting in enhanced environmental, thermal, and light stabilities for the resultant cost-effective high-performance CTL-free PSCs.