Improved hybrid polymer/PbS quantum dot infrared phototransistors incorporating single-layer graphene

The optical responsivity of bulk-heterojunction field effect phototransistors (BH-FEpTs) based on poly [2-methoxy-5-(2'-ethylhexyloxy-p-phenylenevinylene)] (MEH-PPV) and PbS quantum dot hybrids is very low. A main reason for the low responsivity is the low carrier mobility of the blends. To overcome the shortcoming, graphene with high carrier mobility (similar to 200,000 cm(2)V(-1)s(-1)) can be used for improving the responsivity of BH-FEpTs. However, the influence of monolayer graphene on the photo response of BH-FEpTs still has been not studied. In this papers, BH-FEpTs and GBH-FEpTs (single layer graphene beneath the BH layer in BH-FEpTs) were fabricated. Experimentally, the GBH-FEpTs showed ultrahigh mobility for both holes and electrons (mu(H) and mu(E)) of 183 and 169 cm(2)V(-1)s(-1), while 11.3 and 6.2 cm(2)V(-1)s(-1) in BH-FEpT. Due to the greatly promoted carrier mobility and highly ordered channels for GBH-FEpTs, higher alpha, mu and beta are obtained for GBH-FEpTs. The responsivity of GBH-FEpTs is improved to 10(1) A/W, which is two orders magnitude larger than BH-FEpTs (10(-1) A/W).