Interfacial linkage and carbon encapsulation enable full solution‐printed perovskite photovoltaics with prolonged lifespan

Perovskite solar cells (PSCs) have witnessed an overwhelming success in their skyrocketed power conversion efficiencies (PCEs) within a short period, but a fully solution-processed fabrication of PSC multilayer stack has not been achieved. Herein, we report to fabricate the simplified PSCs with perovskite layer sandwiched and encapsulated between carbon-based electron transport layer (ETL) and counter electrode (CE) via a fully blade-coated process. A self-assembled monolayer of amphiphilic silane (AS) molecules on transparent conducting oxide (TCO) substrate appeals to the fullerene ETL deposition and preserves its integrity against the solvent damage induced by perovskite precursor. The AS serves as a“molecular glue”to strengthen the adhesion toughness at the TCO/ETL interface via robust chemical interaction and bonding, which remarkably facilitates the interfacial charge extraction, increases the PCEs by 77% and reduces the hysteresis. A champion PCE of 18.64% has been achieved for the fully-printed devices, which is one of the highest reported values for the carbon-based PSCs. AS-assisted interfacial linkage and carbon materials-assisted self-encapsulation remakably enhance the stability of the resultant PSCs, which did not experience any performance degradation when stored at ambient conditions for more than 3000 hours. This work provides a novel strategy to tackle the incompatibility issue of depositing each functional layer by using a full solution process and offers an additional promise of constructing efficient perovskite-based optoelectronics with prolonged lifespan in a low-cost manner.