PbS colloidal quantum dot photoconductive photodetectors: Transport, traps, and gain
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(Color online) Determination of sensitizing centers via photocurrent thermal quenching. (a) Photocurrent as a function of temperature at two illumination levels. The activation energy of the photocurrent is determined by the mobility activation energy. At higher temperatures photocurrent quenching is observed. (b) Photocurrent quenching taken as the photocurrent at higher temperatures with the mobility contribution component subtracted. The slope of the quenching provides the depth of the sensitizing centers from the conduction band. Two sensitizing centers are discovered with energy depths of and from the conduction band.
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(Color online) Determination of sensitizing centers via transient photocurrent measurements. (a) Transient photocurrent measurements as a function of temperature exhibit three exponential decay components with time constants at room temperature of , , and at . (b) The plot shows the dependence of the time constants as a function of temperature and provides additional information on the sensitizing centers’ depths. This technique reveals in the addition of the 0.1 and another center from the conduction band. (c) Band diagram of the proposed model for photoconductivity in PbS quantum dot photodetectors.
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