[18a-PB01-1~25] 12.5 Organic and hybrid solar cells

[18a-PB01-5] Impact of halogen substitution on properties and photovoltaic performances in dithienonaphthobisthiadiazole-based π-conjugated polymers

〇(M1)Shota Suruga¹, Tsubasa Mikie¹, Itaru Osaka¹ (1.Hiroshima Univ.)

Keywords:Organic photovoltaic cells, Conjugated polymers, Organic semiconductors

A crucial issue in improving the power conversion efficiency (PCE) of organic photovoltaic cells (OPVs) is how to manage the energetics of polymer/nonfullerene acceptors (NFAs) blends. Halogen substitution is an effective method for precise control of energy levels of π-conjugated materials. In particular, the substitution of electron-withdrawing fluorine and chlorine atoms into p-type semiconductor polymers is expected to lower the HOMO energy levels that would improve the open-circuit voltage (V_OC). We recently developed a dithienonaphthobisthiadiazole (TNT)-based π-conjugated polymer with a benzodithiophene unit having fluorinated alkylthienyl substituents, named PTNT1-F, which demonstrated high PCEs of more than 16% with high V_OC of 0.88 V in NFA-based OPVs. Here, we have newly synthesized TNT-based polymers having hydrogen and chlorine groups at the β-position of the alkylthienyl substituents, namely PTNT1 and PTNT1-Cl, and investigated the impact of halogen substitution on the properties and OPV performance in the TNT-based polymers.