Fig. 1. XRD patterns of samples S1-S6

Fig. 2. Optical microscope surface morphologies of samples S1-S6. (a) Sample S1; (b) sample S2; (c) sample S3; (d) sample S4; (e) sample S5; (f) sample S6

Fig. 3. SEM surface morphologies of samples S1-S6. (a) Sample S1; (b) sample S2; (c) sample S3; (d) sample S4; (e) sample S5; (f) sample S6

Fig. 4. Schematic diagram of optoelectronic property test and optoelectronic properties of PbS thin films at different optical power densities. (a) Schematic diagram of optoelectronic property test; (b) I_ph; (c) R; (d) D^*

Fig. 5. Thicknesses and optoelectronic properties of PbS thin films. (a) Thicknesses of samples S1-S6; (b) I_dark of samples S2-S6;(c) R of samples S2-S6; (d) D^* of samples S2-S6

Fig. 6. Response diagram of sample S5 at high frequency. (a) Normalized response curve at 4 kHz; (b) partial magnification of Fig. 6(a)