Validating the Novel Electron Transport Layer with the Use of Experimentally Studied D18:Y6 Bulk Heterojunction Solar Cell

Abstract Organic solar cells (OSC) are showing steady efficiency improvement due to the development in the materials synthesis, sophisticated characterization techniques, in‐depth understanding of materials and devices. In the recent years, bulk heterojunction OSC with a non‐fullerene acceptor /polymer acceptor shows significant enhancement in efficiency (≈19%). Efficiency of the polymer acceptor OSCs is much higher than the fullerene derivative‐based acceptors. In this work, OSC simulations are done using D18 donor and Y6 acceptor bulk heterojunction as a photoactive layer. As a first step, validity of the experimental results for ITO/PEDOT:PSS/D18:Y6/PDIN/Ag structure is done. To investigate efficiency, 2,8,15‐trifluoro‐3,9,14‐tris(heptylsulfonyl)diquinoxalino[2,3‐a:2′,3′‐c]phenazine (HATNASO2C7‐Cs) electron transport layer is validated in place of PDIN in the following device structure, ITO/PEDOT:PSS/D18:Y6/HATNASO2C7‐Cs/Ag. Energy level matching of the HATNASO2C7‐Cs is well aligned compared with PDIN at the cathode interface. Device simulation optimization are carried out for various photoactive layer, ETL and HTL condition. Highest efficiency of 20.99% is obtained for ITO/PEDOT:PSS/D18:Y6/HATNASO2C7‐Cs/Ag when the HATNASO2C7‐Cs thickness, bandgap, electron affinity, carrier mobility, and defect density is matched for ≈30 nm, ≈2.8 eV, ≈4.16 eV, ≈2 × 10 −3 cm 2 V −1 s −1 , and 10 14 cm −3 respectively. Obtained results are discussed in details and results will be helpful for preliminary understanding of the system.