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.