Transparent photodiodes consisting of p-type CNT/n-type ZnO heterojunction with graphene electrodes

We herein report on transparent heterojunctions consisting of p-type CNT and n-type ZnO films on quartz substrates. For transparent electrodes, Al-doped ZnO film and graphene were used for ZnO and CNT films, respectively. These devices exhibited a rectifying diode behavior with an ideality factor of about 1.46 and an optical transmission over 80% in the visible range. Upon light illumination, the photocurrent was enhanced, demonstrating that transparent photodiodes can be achieved by using CNT/ZnO heterojunctions and graphene electrodes.