Hot-injection synthesis of ultrasmall CuIn3Se5 quantum dots and production of ink-coated films. (November 2020) - Ghali, M.
Abstract: For the first time, we synthesized ultrasmall colloidal CuIn3 Se5 quantum dots (QDs) with an average diameter of 3.5 nm and they were used to obtain nearly continuous ink-coated films by the hot-injection method. Copper chloride, indium chloride, and selenium were used as reagents in oleylamine as the solvent to synthesize CuIn3 Se5 QDs without other organometallic precursors. The synthesized CuIn3 Se5 QDs had a cubic crystal structure and they exhibited a strong quantum confinement effect according to their optical absorption spectra. The as-deposited and annealed thin films prepared from an ink solution containing these QDs exhibited p-type characteristics, a high band gap, and low surface roughness. The optical constants were determined by interference-free mathematical modeling for the as-deposited and annealed films obtained with the synthesized CuIn3 Se5 QDs. Moreover, under 1 sun of simulated radiation, the photocurrent was greatly enhanced (>1000%) for the annealed CuIn3 Se5 QD film compared with the as-deposited film. These results suggest that colloidal CuIn3 Se5 QD films could potentially be used as an active layer in low-cost highly efficient Cu(In, Ga)Se/CdS thin film solar cells. Highlights: First time synthesis of ultra-small CuIn3 Se5 material in the quantum dots regime using solution-based method. Ink-coated thin films prepared from these CuIn3 Se5 quantum dots, have been made using controlled film applicator. The coated CuIn3 Se5 films display p-type character, low-surface roughness and strong photo-responsive behavior.