Modulation of Three p-Type Polymers Containing a Fluorinated-Thiophene-Fused-Benzotriazole Unit To Pair with a Benzotriazole-Based Non-fullerene Acceptor for High <i>V</i> <sub/>OC</sub> Organic Solar Cells

摘要： Three 6-?uoro-thieno[2′,3′:4,5]benzo[1,2-d][1,2,3]triazole (fBTAZT) containing copolymers, named as PfBTAZT-H, PfBTAZT-F, and PfBTAZT-Cl, were employed to pair with a benzo[1,2-d][1,2,3]triazole (BTA) based non-fullerene acceptor BTA3 for the applicaition in organic solar cells (OSCs). By introducing ?uorine or chlorine atoms into the thiophene side chains on BDT units, the highest occupied molecular orbital (HOMO) energy levels of polymers shift down in sequence, and PfBTAZT-Cl shows an obvious blue-shift of absorption spectrum. PfBTAZT-F:BTA3-based OSC attains a VOC of 1.05 V, a JSC of 11.83 mA cm?2, and FF of 0.62, leading to a PCE of 7.69%, which are higher than that of PfBTAZT-H:BTA3 (VOC = 0.99 V, JSC = 11.60 mA cm?2, FF = 0.58, and PCE = 6.65%) due to its well-matched HOMO energy level, higher charge mobilities, and favorable ?lm morphology. More surprisingly, chlorinated polymer PfBTAZT-Cl obtains the highest VOC of 1.20 V and PCE of 8.00%, which is attributed to the lowest HOMO energy level, largely decreased voltage loss (ΔVloss = 0.56 V compared to 0.77 V for PfBTAZT-H:BTA3 0.71 V for PfBTAZT-F:BTA3), more complementary absorption with that of BTA3, and e?ective charge generation. Our results demonstrate that chlorination is an e?ective approach to realize a high PCE and VOC and thiophene-fused benzotriazole (BTAZT) based polymers are also good candidates for material combinations in “Same-A-Strategy” (SAS).