Dithienopyrrole Based Small Molecule with Low Band Gap for Organic Solar Cells

Abstract A low band gap acceptor‐donor‐acceptor (A‐D‐A) small molecule donor material, named DR3TDTN, has been designed and synthesized for solution‐processed organic solar cells. DR3TDTN shows narrow optical band gap with value of 1.49 eV and broad absorption spectrum from 300 to 820 nm. The HOMO and LUMO energy levels of DR3TDTN are −4.74 and −3.26 eV, respectively. The optimized photovoltaic device based on DR3TDTN:PCB71BBM blend film shows a power conversion efficiency of 3.03% with an open‐circuit voltage of 0.67 V, a short‐circuit current of 8.22 mA·cmP−2 and fill factor of 0.55.