Photoconductivity and electroluminescence in lead iodide based natural quantum well structures

For the natural quantum well structures of (C6H5 - C2H4NH3)2 - PbI4 and (C6H5 - C2H4NH3)2(CH3NH3) - Pb2I7, step-like features in the absorption and photo-current spectra were identified as 2D band edge transitions from their temperature dependence. Photocurrent along the c-axis is much smaller than that along the well plane, revealing the large anisotropy of the electronic band structure, and shows a plateau in the current-voltage curve, which can be explained in terms of Wannier-Stark localization in the materials. Electroluminescence from free excitons was observed at a relatively low field (10 kV cm-1) along the wells below 200 K.