High efficiency perovskite solar cells using nitrogen-doped graphene/ZnO nanorod composite as an electron transport layer

We demonstrate for the first time, the photovoltaic performance of perovskite solar cells (PSCs) by employing nitrogen-doped graphene/ZnO nanorod nanocomposites (NG-ZnO NR NCs) as an electron transport layer (ETL). A series of PSCs are fabricated by varying the NG concentration from 0 to 1 wt% with an increment of 0.2 wt% in ZnO NRs having a device structure of FTO/NG-ZnO NR NCs/CH3NH3PbI3/Spiro-MeOTAD/Ag. The perovskite films grown on NG-ZnO NR NCs exhibited a uniform film with high surface coverage area with an improved crystallinity. By employing photoluminescence measurements, it was found that NG-ZnO NR NCs reduced the interfacial resistance by improving charge carrier extraction, which is in correlation with an improvement in photocurrent and fill factor in the corresponding devices. At an optimized concentration of NG (0.8 wt%) in ZnO NRs, PSCs obtained an improvement in photocurrent from 17.38 mA/cm(2) to 21.98 mA/cm(2) and the power conversion efficiency from 12.87% to 16.82%, respectively.