Ultrafast photoresponse organic phototransistors based on pyrimido[4,5-g]quinazoline-4,9-dione polymer

We report the photoresponse characteristics of a pyrimido[4,5-g] quinazoline-4,9-dione (PQ) based polymer, PPQ2T-BT-24, which served as an active channel layer in organic phototransistors (OPTs). OPTs using this polymer showed very short rise time of 3 ms and fall time of 59 ms, photoresponsivity (R) of 0.24 and external quantum efficiency (EQE) of 50%. When PC61BM was incorporated into PPQ2T-BT-24, a significantly shortened fall time of 8 ms along with a much-improved rise time of 1 ms were realized. These response times are among the best values reported for OPTs. The R and EQE of the devices using this polymer blend also increased to 0.88 A W-1 and 189%, respectively.