Air-stable synthesis of near-infrared AgInSe2 quantum dots for sensitized solar cells

The synthesis of highly photoluminescent quantum dots (QDs) is critical for QD sensitized solar cells. As a typical I-III-VI compound, AgInSe2 QDs with high quality were often synthesized by the hot-injection method with a stock solution of selenium powder in oleylamine, trioctylphosphine used as capping agent. This work introduces selenium dioxide as a selenium source to synthesize high-quality AglnSe(2) with the tunable composition by a heating-up method in air. The gradient compositions of AglnSe(2) QDs were achieved by the control of the relative feeding ratio of Ag/In precursors. The emission peaks of AglnSe(2) QDs locate between 740 similar to 1080 nm with as longer lifetime as 450 ns, depending on the ratio of Ag/In in AgInSe2. The ligand exchange was adapted to assist adsorption onto the TiO2 photoanode. Under a complete solar illumination, AgInSe2 QDs-sensitized solar cells demonstrated the best power conversion efficiency of 3.31%. The current density-voltage curves of the best solar cells showed that the short circuit current was 18.16 mA.cm(-2), the open-circuit voltage was 0.35 V, and the fill factor was 51%. The improved photoelectric performance of the AglnSe(2) QD is thought as the attribution of theirs enhanced PL lifetime and broader spectral response reaching 1100 nm. This method proposes a new strategy for the synthesis of AglnSe(2) QDs with high quality.

Automated summary

The study synthesized high-quality AgInSe2 QDs using selenium dioxide as the selenium source, achieving gradient compositions by controlling the relative feeding ratio of Ag/In precursors. The QDs showed a broader spectral response and longer fluorescence lifetime, enhancing their photoelectric performance.