Fig. 1. XRD of Cs₃Cu₂Br₅ thin films grown at different substrate temperatures

Fig. 2. Surface SEM images of Cs₃Cu₂Br₅ thin films grown at different substrate temperatures

Fig. 3. EDS spectrum of Cs₃Cu₂Br₅ thin film

Fig. 4. The absorption spectrum of Cs₃Cu₂Br₅ thin film grown at 50 ℃，and the absorption spectrum of Cs₃Cu₂Br₅ thin films grown at different substrate temperatures

Fig. 5. PL and PLE spectra of Cs₃Cu₂Br₅ thin films deposited at 50 ℃

Fig. 6. PL spectra of Cs₃Cu₂Br₅ thin films grown at different substrate temperatures and Diagram of the relationship between the full width at half height （FWHM） of PL and temperature

Fig. 7. Structural schematic of heterojunction device

Fig. 8. Current voltage curve （logarithmic form） and on/off ratio curve of Cs₃Cu₂Br₅/Si photodetector under dark and light conditions （illustration）

Fig. 9. The current-voltage curves of Cs₃Cu₂Br₅/n-Si devices under different light intensities under I-V bias voltage and Spectral responsivity and detection rate of Cs₃Cu₂Br₅/Si device under -1 V bias voltage （illustration）

Fig. 10. Band of Cs₃Cu₂Br₅/n-Si according to Anderson model