A high performance green-sensitive organic photodiode comprising a bulk heterojunction of dimethyl-quinacridone and dicyanovinyl terthiophene

A fullerene-free bulk-heterojunction (BHJ) organic photodiode (OPD) with high efficiency and green-color selectivity is reported. Using N,N-dimethyl quinacridone (DMQA) as a donor and dibutyl-substituted dicyanovinyl-terthiophene (DCV3T) as an acceptor, a maximum external quantum efficiency (EQE) of over 67% at 540 nm was achieved at -5 V bias. The OPD performance together with their electrical and optical behaviors were investigated by varying the ratio of donor and acceptor components and measuring the absorption coefficient, charge carrier generation, and charge transport. The composition rich in DMQA exhibited a high yield of photogenerated charge carriers and a low absorption intensity, whereas the material rich in DCV3T had a high absorption intensity and low yield of charge carriers. It was found that the 1 : 1 ratio of components showed the best device performance due to its relatively high absorption and efficient photogeneration of charge carriers. Furthermore, electrical characterization of our BHJ OPDs indicated that a balance of electron and hole mobilities is important for enhancing EQE.