Carbazole core derived dyes: New non-fullerene acceptor for all small-molecule organic solar cells with very high open-circuit voltage of 1.12 V

Abstract

We have design and synthesized two similar A-π-D-π-A structured V-shaped small molecular non-fullerene acceptors named as BYG3 and BYG4 for BHJ-OSCs applications. The molecular architecture of BYG3 and BYG4 consists of an electron rich carbazole as central core, benzothiadiazole as π-spacer and finally it is end caped with naphthamide unit via ethyne linker. The major difference among BYG3 and BYG4 non-fullerene acceptors is fluorine atom substitution at benzothiadiazole unit and the effects of fluorine atom on its optical, electrochemical and photovoltaic properties were well discussed. The optoelectronic properties and band gap of BYG3 and BYG4 acceptors were well synchronized to small molecule donor SMD. Therefore, all small molecule BHJ-OSCs device were constructed using BYG3 and BYG4 as acceptors and small molecule (SMD) as donor results power conversion efficiency (PCE) of 8.09% and 8.57% with high open circuit voltages (Voc) of 1.12 V and 1.05 V respectively. Also, BYG4 based OSCs devices were displayed high values of short-circuit current density (Jsc) and fil factor (FF) are higher for than that for BYG3, may be related to the more effective exciton dissociation and charge transfer in the SMD:BYG4 active layer than that for SMD:BYG3 counterpart. However, the larger value of Voc for the BYG3 based OSCs than BYG4 counterpart may be related to the up-shifted LUMO energy level of BYG3.