High-performance nonfullerene polymer solar cells based on chlorinated quinoxaline copolymer with a high short-circuit current density

Abstract

In organic solar cells, the absorption range and extinction coefficient of the active layer not only affect the charge separation and carrier transfer efficiency of excitons, but also influence the JSC, and thus the device efficiency. Herein, an efficient nonfullerene polymer solar cells (NF–PSCs) based on a medium-bandgap (MBG) polymer donor PBDTTS-TClQx comprising chlorinethiophene quinoxaline (Qx) unit and a small molecule nonfullerene acceptor (SM-NFA) Y6 is developed. The PBDTTS-TClQx shows a strong absorption in the wavelength region of 330∼750 nm with an optical band gaps (Egopt) of 1.68 eV, which is well complementary with that of Y6 (1.33 eV) and facilitates achieving of high short-circuit current (JSC) in PSCs. As a result, the PBDTTS-TClQx:Y6-based PSCs achieved a power conversion efficiency (PCE) of 14.28% with a JSC of 25.9 mA cm−2. The JSC of 25.9 mA cm−2 achieved is among the highest reported for Qx-based polymer donors in PSCs.