14.46% Efficiency small molecule organic photovoltaics enabled by the well trade-off between phase separation and photon harvesting

Small molecule organic photovoltaics (SMPVs) were prepared by utilizing liquid crystalline donor material BTR-Cl and two similar optical bandgap non-fullerene acceptor materials BTP-BO-4F and Y6. The BTPBO-4F and Y6 have the similar optical bandgap and different absorption coefficients. The corresponding binary SMPVs exhibit different short circuit current density (JSC) (20.38 vs. 23.24 mA cm(-2)), and fill factor (FF) (70.77% vs. 67.21%). A 14.46% power conversion efficiency (PCE) is acquired in ternary SMPVs with 30 wt% Y6, companied with a JSC of 24.17 mA cmz, a FF of 68.78% and an open circuit voltage (VOC) of 0.87 V. The improvement on PCE of ternary SMPVs should originate from the well trade-off between phase separation and photon harvesting of ternary active layers by incorporating 30 wt% Y6 in acceptors. This work may deliver insight onto the improved performance of SMPVs by superposing the superiorities of binary SMPVs with similar optical bandgap acceptors into one ternary cell. (C) 2020 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.

Automated summary

In this study, small molecule organic photovoltaics (SMPVs) were fabricated using a liquid crystalline donor material BTR-Cl and two similar optical bandgap non-fullerene acceptor materials BTP-BO-4F and Y6. The ternary SMPVs with 30 wt% Y6 achieved a high power conversion efficiency of 14.46% due to a well trade-off between phase separation and photon harvesting. Incorporating Y6 into the acceptors improved the performance of SMPVs significantly.