Thickness and illumination intensity dependent performances of broad spectral photodiodes based on n-Si/SnO2/perovskite double heterojunction

Combined with the excellent optoelectronic properties of perovskite in the visible region and Si in the near infrared region, silicon/perovskite heterojunction shows great potential in the field of broad spectral photodetection. We report on the fabrication of photodiodes based on n-Si/SnO2/perovskite double heterojunction with a broad photo response spectral range from 450 to 980 nm and the investigations of the effect of SnO2 layer thickness (dSnO2) on device performance. The result showed that the device performance depends strongly on dSnO2, and that at dSnO2 = 40 nm, the device exhibits an optimal performance with a photo responsivity of 6890 mA/W, an external quantum efficiency of 1005%, and a specific detectivity of 5.31 × 1012 Jones under illumination with a wavelength of 850 nm. The investigation of the effect of illumination intensity (Pint) on the photocurrent (Iph) as well as on device performances showed that the Iph ∼ Pint curve can be divided into three regions, that is, the lower intensity region (LIR), the higher intensity region (HIR), and the transitional region, among which the LIR and HIR can be well fitted by the equation Iph∝Pintγ, with factors γL and γH, respectively. The variations of γL and γH with SnO2 layer thickness were investigated, and their underlying photo physics was analyzed. The achieved results provide a novel insight into photocarrier dynamics in related devices.