(a) Schematic device structure of the OIHP photodetectors. (b) Cross-section scanning electron microscope (SEM) image of an OIHP photodetector. Inset: a tilted view of perovskite and C₆₀/2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) layer. (c) The trap density of states curve versus demarcation energy with or without C₆₀ in the devices. (d) EQE of the OIHP photodetector at zero bias. (e) The specific detectivity of the OIHP photodetector at different light wavelengths under −0.1-V bias voltage. Inset: The noise current of the OIHP photodetector at −0.1 V. (f) The linear dynamic range of the OIHP photodetector under an LED illumination of various light intensities. The solid line represents linear fitting to the data. (g) The transient photocurrent (TPC) curves of the devices with different areas from 7 mm² down to 0.04 mm². TPC lifetime: 115.1 ns for 7 mm²; 35.3 ns for 2 mm²; 17.9 ns for 1 mm²; and 9.0 ns for 0.5 mm². Inset: 2.7 ns for 0.15 mm²; 1.0 ns for 0.04 mm². (h) TPC curves of the perovskite photodetectors with different C₆₀ thicknesses. TPC lifetime: 1.4 ns for 50 nm and 2.5 ns for 80 nm (from Ref. [25]).