Enhanced efficiency of polymer solar cells via simple fluorination on the π-bridge of polymer donors

Abstract

In this contribution, a novel fluorinated polymer based on the well-known J52, using the newly developed 3-fluorothiophene as π bridges on the conjugated main chain, named J52-FTh , was synthesized and was used as polymer solar cells (PSCs) donor material. The effects of fluorinated π bridge on the polymer's thermal stability, light absorption, energy level, molecular configuration and photovoltaic performance were systematically studied. It demonstrated that J52-FTh exhibited an enhanced absorption, a narrower optical band gap, a low-lying the highest occupied molecular orbitals (HOMO) energy level and better coplanar compared with J52 without any fluorine substituent on its π bridges. The non-fullerene PSCs based on J52-FTh :ITIC (1:0.8, w/w) achieved a high PCE of 13.32% with a V OC of 0.92 V, a J SC of 21.29 mA cm −2 and an FF of 68%, which was much better than the PSCs based on J52:ITIC with a PCE of 5.51%. The results indicated that fluorination on the polymer's main chain was a simple and efficient strategy toward high efficiency. A novel fluorinated polymer based on the well-known J52, using the newly developed 3-fluorothiophene as π bridges on the conjugated main chain, named J52-FTh , was synthesized and was used as polymer solar cells (PSCs) donor material. The PSCs based on J52-FTh :ITIC achieved a high PCE of 13.32% with a V OC of 0.92 V, a J SC of 21.29 mA cm −2 and a FF of 68%, which was superior to that of the binary PSCs based on J52:ITIC. • A novel fluorinated polymer based on the well-known J52, using the newly developed 3-fluorothiophene as π bridges, named J52-FTh , was synthesized. • The effects of fluorinated π bridge on the polymer’s thermal stability, light absorption, energy level, molecular configuration and photovoltaic performance were systematically studied. • J52-FTh exhibited an enhanced absorption, a narrower optical band gap, a low-lying HOMO energy level and better coplanar compared with J52 without any fluorine substituent on its π bridges. The non-fullerene PSCs based on J52-FTh :ITIC achieved a high PCE of 13.32%, which was much better than the PSCs based on J52:ITIC. • The results indicated that fluorination on the polymer’s main chain was a simple and efficient strategy toward high efficiency.