Fig. 4
Mechanism study of the 2D perovskite based narrowband photodetection. a Schematic of the 2D perovskite single crystal-based lateral device with illumination from back side (Config. 2) and front side (Config. 3). b Normalized EQE spectra of the (BA)2(MA)Pb2I7 devices with three different measurement configurations. The peaks of the spectra are marked by arrows with different color. Blue arrow: band-to-band (B); green arrow: free exciton (X0); red arrow: self-trapped state (Xt). c Normalized EQE spectra of device with Config. 3 under different biases. Inset: the dependence of the EQE value of B peak, X0 peak, and Xt peak on bias. The dashed lines are used to guide the eye. d,e,f Schematic of the carrier generation and extraction process for the above mentioned three different measurement configurations. Red: long wavelength light and bulk-generated carriers. Green: short-wavelength light and surface-generated carriers. g,h The thickness dependence of normalized EQE spectra of the (BA)2(MA)Pb2I7 devices for Config. 1 (g) and Config. 2 (f), respectively. i Thickness dependence of peak position under the same applied electrical bias and normalized EQE under the same applied electrical field extracted from the EQE spectra in g. The dashed lines are used to guide the eye
