Abstract

Organic solar cells (OSCs) have experienced a rapid progress in terms of efficiency in both single and tandem structures. Herein, two‐terminal (2T) tandem design is fabricated using PV2000:PCBM (1.65 eV) and PM6:Y6 (1.3 eV) blends as bottom and top cells, respectively. The role of transporting and recombination layers on photovoltaic (PV) parameters is studied. The impedance and transmittance results indicate that using SnO 2 nanocrystals (NCs) as an electron transporting layer (ETL) in both subcells, the fill factor (FF) and the open circuit voltage ( V OC ) of the tandem device are increased drastically, mainly due to the lower resistance of the SnO 2 layer and its higher transmittance as compared with the ZnO ETL. Moreover, it is found that the V OC and FF losses are reduced using poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/Ag (1 nm)/SnO 2 NCs as a recombination layer in the tandem design. After proper optimization, a tandem OSC with a V OC of 1.61 V and an efficiency of 14.4% is achieved, which shows great operational stability as well. In addition, the current match and efficiency of the tandem device are increased up to 12.94 mA cm −2 and 15.2%, respectively, by applying a nanotextured anti‐reflection layer on the back of the device.