Three-dimensional pyramidal CsPbBr3/C8BTBT film heterojunction photodetectors with high responsivity and long-term stability

A low pressure chemical vapor deposition (CVD) was developed to fabricate CsPbBr3 perovskite film with three-dimensional (3D) pyramidal surface for constructing high-performance and stable photodetectors. The pyramidal CsPbBr3 film is beneficial to increase the absorption and reduce the reflection of light, leading to the improvement of photodetector performance. Moreover, the responsivity and stability could be further improved by constructing a hybrid inorganic/organic film photodetector due to the modification of organic semiconductor C8BTBT on the surface holes and grain boundary junction of CsPbBr3 film. The responsivity of CsPbBr3/C8BTBT photodetector has increased 9.55 times, from 0.42 A/W to 4.01 A/W at 405 nm. The photocurrent of CsPbBr3/C8BTBT photodetector could maintain over 94% of the initial current as exposed to 35% humidity for six months. More importantly, the photocurrent in the current-time (I-T) diagram is stable without attenuation even after the on/off states of the photodetector lasts for 3000 s. The excellent stability under ambient condition resulted from the stable CsPbBr3 film fabricated via CVD and the C8BTBT filled at the perovskite grain boundary. The results have guided significance for the preparation of high-performance and stable perovskite optoelectronic devices.