High response organic UV-blue photodetector with low operating voltage using chemical vapor deposited poly(p-phenylenevinylene)

High response UV-blue photodiodes are fabricated with chemical vapor deposited poly(p-phenylenevinylene) (PPV) as donor and thermally evaporated C-60 as acceptor. Chemical vapor deposition (CVD) has the advantage that scaling up for deposition on large area substrates is feasible. High efficiency is achieved by optimizing the device structure using the optical electric field distribution calculated from transfer matrix simulations. The photodiode operates in the 330 nm to 500 nm wavelength range (UV-A and blue) with a peak responsivity of 148 mA/W at 370 nm and 180 mA/W at 450 nm under a low bias of -1.5 V. A comparison between the photodiodes of CVD grown PPV with spin coated PPV shows that growth by CVD results in significant improvement in responsivity. The high responsivity is attributed to the optimized device geometry and enhanced hole mobility in CVD grown PPV.