A high-speed photocurrent multiplication device based on an organic double-layered structure

A high-speed photocurrent multiplication device that has an organic double-layered structure was fabricated. In this device, the improvement in the uniformity of the organic films, caused by inserting an additional amorphous-like organic underlayer, enabled high-electric-field operation of the device. Owing to efficient carrier photogeneration under the application of higher voltages, the response time of the multiplied photocurrent became shorter without a decrease in the multiplication rate, and showed clear saturation above 18 V. At a high applied voltage of 20 V, a large multiplication rate of ${\text{1.7×10}}^5$ -fold, with a high-speed response of 3.7 s, was achieved. A rise time of only 26 ms required for the 1000-fold multiplication suggests that the multiplication device could potentially be applied to a practical imaging device.