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

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 cm² V⁻¹ s⁻¹, and 10¹⁴ cm⁻³ respectively. Obtained results are discussed in details and results will be helpful for preliminary understanding of the system.