TUNING THE PROPERTIES OF PUSH-PULL MOLECULAR SYSTEMS VIA FLUORINE (F), TRIFLUOROMETHYL (CF3) AND PENTAFLUOROSULFANYL (SF5) GROUP SUBSTITUTION

Push-pull molecular systems have played a significant role for development of efficient materials for organic electronic applications. A group of push-pull organic small molecular system derived from phenothiazine donor and benzothiadiazole acceptor with donor-π-acceptor-π-acceptor architecture were designed and studied using density functional theory method to explore the influence of fluorine enrichment on the optoelectronic and photovoltaic properties. The molecular design adopted for fluorine enrichment vary with respect to fluorine, trifluoromethyl and pentafluorosulfanyl group substitution on the benzothiadiazole unit. The effect on the optoelectronic properties, the HOMO–LUMO gap and photovoltaic properties upon fluorine enrichment through fluorine, trifluoromethyl and pentafluorosulfanyl group functionalization were explored. The open-circuit photovoltage and power conversion efficiency for designed push-pull small molecular donors were presented with phenyl-C71-butyric acid methyl ester (PC71BM) acceptor. The trend observed for open-circuit photovoltage shows that incorporation of trifluoromethyl and pentafluorosulfanyl group can be a promising way to improve the open-circuit photovoltage and power conversion efficiency of bulk heterojunction solar cells.