Fig. 3

X-ray Photoelectron Spectrum (XPS) and optoelectronic properties. a Pb 4f XPS spectrum, b I 3d XPS spectrum and c O 1s XPS spectrum of PbS-I NCs. d Transient photoluminescence of PbS-I NC solution. e J-V curve of space charge limited current device of PbS-I NCs. Device structure: Ag/PbS-I/Ag. f Transfer characteristics of PbS-I NCs based FET