All solution-processed organic photocathodes with increased efficiency and stability via the tuning of the hole-extracting layer

Photoelectrodes based on solution-processed organic semiconductors are emerging as low-cost alternatives to crystalline semiconductors and platinum. In this work, the performance and stability of P3HT:PCBM\ MoS3-based photocathodes are considerably improved by changing the hole-extracting layer (HEL). Oxides such as reduced graphene oxide, nickel oxide or molybdenum oxide are deposited via solution processes. With MoOx, a photocurrent density of 2 mA cm(-2) during 1 h is obtained with the processing temperature lower than 150 degrees C - thus compatible with flexible substrates. Furthermore, we show that the performances are directly correlated with the work function of the HEL material, and the comparison with solid-state solar cells shows that efficient HELs are not the same for the two types of devices.