Remarkably high performance of organic photovoltaic devices with 3,9-bis(2-methylene- (3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexyl meta-phenyl)-dithieno[2,3-d:2′,3′-d’]-s-indaceno[1,2-b:5,6-b’]dithiophene)- ethylhexyloxy] photoactive acceptor under halogen light illumination

Alternative acceptors for fullerene-derivatives need to be considered for indoor organic photovoltaics (OPVs) due to their spectrally inefficient light absorption ability and photo-instability which limits performance. Here, we report a highly efficient and photo-stable indoor OPV comprising an amalgamation of a wide band-gap donor(poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1,2-b:4,5-b’]dithiophene))-alt-(5,5-(1′,3′-di-2-thienyl-5′,7′-bis(2-ethylhexyl)benzo[1′,2′-c:4′,5′-c’]dithiophene-4,8-dionz) and a modified ITIC-based NFA (3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis (4-hexylmeta-phenyl)-dithieno [2,3-2′,3′-d’]-s indaceno [1,2b:5,6b] dithiopheneethylexyloxy) (m-ITIC-O-EH)) with alkoxy side chains. Due to its excellent absorption properties in the near-infrared region, the m-ITIC-O-EH-based OPV exhibited an extraordinarily high maximum output power density (P_max) (95.6 μW/cm²), >3 times greater than the P_max (31.9 μW/cm²) of a reference fullerene acceptor-based (PC₇₀BM) OPV under a 1000 lx halogen lamp (P_in = 8.4 mW/cm²). Furthermore, the m-ITIC-O-EH-based OPV exhibited satisfactory photo-stability with >80% retention of its initial power conversion efficiency (PCE) under the continuous light soaking of the halogen lamp (1000 lx) for 12 h. The high-indoor performance of the alkoxy-substituted NFA-based OPVs highlights their potential for implementation in Internet of Things applications.