An ultraviolet, self-powered, and large area photodetector based on a n-SnO2/p-spiro-OMeTAD organic–inorganic heterojunction

Abstract

Self-powered photodetectors are of importance for practical applications. However, inorganic heterojunctions for photodetectors often contain defect states due to lattice mismatch. Herein, an ultraviolet photodetector based on a n-SnO₂/p-spiro-OMeTAD organic–inorganic heterojunction (OIH) was fabricated by spin-coating. On the basis of spectral data (absorption, reflection, and ultraviolet photoemission spectra) and the Hall effect measurements, energy level alignment at the SnO₂/spiro-OMeTAD interface is unveiled. The results of linear sweep voltammetry indicate that an ohmic contact is formed at the FTO/SnO₂ interface. The responsivity and detectivity of the SnO₂/spiro-OMeTAD photodetector are 1.42 mA W⁻¹ and 3.10 × 10⁷ Jones at 386 nm with 30 W m⁻², respectively. In addition, the performance of the device has no degradation for nearly 1000 hours. The working mechanism of the device based on SnO₂/spiro-OMeTAD OIH is that when the device is irradiated with UV light, electrons transfer from the SnO₂ layer to FTO, and holes transfer from the spiro-OMeTAD layer to Au. Finally, large area devices with 10 × 10 cm (active area 52 cm²) were prepared by the spraying method. In the rotating state, large area devices can effectively detect ultraviolet light. The device has potential to be applied as a high-performance, large-area ultraviolet photodetector.