Co-doping of tellurium with bismuth enhances stability and photoluminescence quantum yield of Cs 2 AgInCl 6 double perovskite nanocrystals.

The co-doping of double perovskites is a useful approach in terms of improving their stability and photoluminescence quantum yield. Herein, Bi 3+ and Te 4+ cations have been co-doped into Cs 2 AgInCl 6 nanocrystals. Doping with Te 4+ cations promotes radiative recombination of self-trapped excitons due to increased defect formation energies of silver and indium vacancies, according to experimental and theoretical results. When used in excess, the TeO 2 precursor would generate residual TeO 2 , Te 2 O 3 Cl 2 , R 2 TeO, or all three of them, which confined undesired chlorine ions on oxygen vacancies to counteract the pull from the Cs 2 AgInCl 6 host, resulting in improved coordination with surface oleic acid ligands. As a result, 1% Bi and 8% Te co-doped Cs 2 AgInCl 6 nanocrystals reach a high photoluminescence quantum yield of 34% and show an improved stability, maintaining over 70% of their original emission intensity after storage for more than 1 month. These findings are important in the context of producing high-performance properly doped double perovskite nanocrystals for optoelectronic applications.