Sb2S3 thickness-dependent lateral photovoltaic effect and time response observed in glass/FTO/CdS/Sb2S3/Au structure

As an interesting one dimensional ribbon material, Sb2S3 has recently attracted much attention in recent years due to its exciting optical properties. However, Sb2S3-based photovoltaic or photoelectronic devices are still in research, and there are many things unknown to us and need to be well studied. In this work, the glass/FTO/CdS/Sb2S3/Au structures were successfully prepared with different Sb2S3 thicknesses, and the lateral photovoltaic effect (LPE) was firstly observed in this structure, suggesting its great potential in position sensitivity detectors (PSD). It is demonstrated that the crystallinity of Sb2S3 film increases, and Sb2S3 film tends to be vertical ribbon orientation with increasing thickness. Owing to the strong light absorption of the thicker Sb2S3 film and its one dimensional ribbon like crystal structure, the LPE in the glass/FTO/CdS/Sb2S3/Au structure improves with increasing Sb2S3 thickness from 350 nm to 800 nm, and the glass/FTO/CdS/Sb2S3(800 nm) structure exhibits an unprecedented performance with position sensitivity as large as 2230.4 mV/mm. Moreover, the time response of photovoltage was also firstly measured in this structure, it is observed that both the rise time and the fall time decrease with increasing thickness from 350 nm to 800 nm, and then increase quickly for 1100 nm film, further verifing that the Sb2S3 thickness-dependent LPE is strongly dependent on the carriers' longitudinal transport time. The very large LPE and the relatively fast response speed observed in the glass/FTO/CdS/Sb2S3(800 nm)/Au structure unveils its great potential applications in the optoelectronic detectors and also bring an insight that the suitable thickness is very crucial in Sb2S3-based devices. (C) 2017 Optical Society of America