International Journal of Energy Research, Vol.44, No.14, 12100-12111, 2020
Benzoselenadiazole-core asymmetricD-A-Asmall molecule for solution processed bulk heterojunction organic solar cells
The present work is accounted on the designing of a new and efficient asymmetric organic chromophore, named 4-(3,5-bis [trifluoromethyl] phenyl)-7-(5 '-hexyl-[2,2 '-bithiophen]-5-yl)-benzo[c [1, 2, 5]selenadiazole, (RT-BSe-F), based on benzoselenadiazole central acceptor building blocks. The acceptor unit of 3,5-bis (trifluoromethyl) benzene and donor unit of alkyl bithiophene attached with benzoselenadiazole central unit showed large impacts on the optical and electrochemical properties. The reasonable optical band gap of similar to 2.02 eV and HOMO of -5.33 eV were obtained by RT-BSe-F chromophore due to a strong electron accepting nature of fluorine based compound. With 3,5-bis(trifluoromethyl) benzene unit, the absorption of RT-BSe-F chromophore was considerably increased to higher wavelength which might enhance the crystallinity of thin film with high hole mobility. RT-BSe-F chromophore was effectively applied to fabricate the solution-processed bulk-heterojunction organic solar cells (BHJ-OSCs) and attained a high power conversion efficiency (PCE) of similar to 3.75% accompanying high J(SC) of similar to 12.56 mA cm(-2), FF of similar to 0.42 and V-OC of similar to 0.71 V. The obtained high PCE might be associated to a high surface energy of TiO2 layer as buffer and the use of high mobility organic RT-BSe-F chromophore.