Boosting performance of perovskite solar cells with Graphene quantum dots decorated SnO2 electron transport layers

Abstract

In this work, Graphene quantum dots (GQDs) was decorated on the SnO2 electron transport layers (ETLs) to boost the performance of perovskite solar cells (PSCs). The power conversion efficiency (PCE) of 21.1% was acquired with the combination of SnO2 and GQDs. Compared with the SnO2-only ETL devices (18.6%), the PCE of SnO2/GQDs based devices is greatly enhanced in PCE by the value of 13.4% as well as in the stability. Investigation reveals that with the combination of SnO2 and GQDs, the open circuit voltage (VOC) and the short circuit current density (JSC) could increase. Various advanced optical and electrical characterizations were carried out to explore the action mechanism of GQDs. The experimental results convinced that the introduction of GQDs leads to the better carrier transportation and extraction by increasing the electronic coupling and matching the energy levels between the perovskite and SnO2 ETL. Also, the perovskite film quality deposited on the GQDs decorated SnO2 ETL is better compared with the SnO2 only. Furthermore, the device stability based on the GQDs modified SnO2 is evidently improved contrast to the SnO2-only device. Its performance kept above 80% of initial value after 720 h storage.