Intrinsic stoichiometry optimization of polycrystalline lead selenide film in the sensitization process by iodine concentration regulation

The stoichiometry influence of polycrystalline lead selenide material on crystalline structure and photoelectric properties was demonstrated. The responsivity of 3.97 A/W was achieved biased at 4 V with the optimal iodine molecular density of 9.1×1011 mm−3 and oxygen pressure of ~0.15 MPa in the sensitization process. The photoelectric performance can be further enhanced with iodine at low iodine molecular density of <1.5×1012 mm−3. It is revealed that a serious deviation of Pb/Se atomic ratio from 1:1 is responsible for the significant decline of responsivity due to over-iodination in the sensitization process. It is helpful to understand the roles of iodine and oxygen in the sensitization of lead salt materials.