Fig. 1. SEM images of single Se-MT, single Se/Spiro-MeOTAD, and cross section of Se/Spiro-MeOTAD. （a） SEM image of single Se-MT； （b） SEM image of single Se/Spiro-MeOTAD； （c） SEM image of cross section of Se/Spiro-MeOTAD

Fig. 2. XRD patterns of Se-MT and Se/Spiro-MeOTAD, and Raman spectra of Se-MT, Spiro-MeOTAD, and Se/Spiro-MeOTAD. (a) XRD patterns of Se-MT and Se/Spiro-MeOTAD; (b) Raman spectra of Se-MT, Spiro-MeOTAD, and Se/Spiro-MeOTAD

Fig. 3. Ultraviolet-visible absorption of Se-MT and Se/Spiro-MeOTAD

Fig. 4. Characteristic curves of photodetectors (inserts are diagrams of device). (a) I-V curves of Se/Spiro-MeOTAD heterojunction device; (b) I-V curves of Se-MT for no illumination and 760 nm wavelength illumination; (c) I-t curves of Se/Spiro-MeOTAD heterojunction device for 0 V bias and 410 nm, 500 nm, and 760 nm illumination and I-t curves of Se-MT under 0.1 V bias and 760 nm illumination

Fig. 5. Responsivity and energy band of photodetectors. (a) Spectral response of Se-MT under 0.1 V bias and Se/Spiro-MeOTAD heterojunction under 0 V bias; (b) schematic illustration of energy levels of Se/Spiro-MeOTAD heterjunction