Highly Efficient Indoor Organic Photovoltaics with Spectrally Matched Fluorinated Phenylene-Alkoxybenzothiadiazole-Based Wide Bandgap Polymers

Abstract

The unique electro-optical features of organic photovoltaics (OPVs) have led to their use in applications that focus on indoor energy harvesters. Various adoptable photoactive materials with distinct spectral absorption windows offer enormous potential for their use under various indoor light sources. An in-depth study on the performance optimization of indoor OPVs is conducted using various photoactive materials with different spectral absorption ranges. Among the materials, the fluorinated phenylene-alkoxybenzothiadiazole-based wide bandgap polymer-poly[(5,6-bis(2-hexyldecyloxy)benzo[c][1,2,5]thiadiazole-4,7-diyl)-alt-(5,50-(2,5-difluoro-1,4-phenylene)bis(thiophen-2-yl))] (PDTBTBz-2F(anti))-contained photoactive layer-exhibits a superior spectrum matching with indoor lights, particularly a light-emitting diode (LED), which results in an excellent power absorption ratio. These optical properties contribute to the state-of-the-art performance of the PDTBTBz-2F(anti):[6,6]-phenyl-C-71 butyric acid methyl ester (PC71BM)-based OPV with an unprecedented high power-conversion efficiency (PCE) of 23.1% under a 1000 lx LED. Finally, its indoor photovoltaic performance is observed to be better than that of an interdigitated-back-contact-based silicon photovoltaic (PCE of 16.3%).