RESUMO
Lead-free double perovskite nanocrystals (A2B'(III)Bâ³(I)X6 NCs) address the instability and toxicity concerns of lead-based counterparts, but their device performance is limited by subpar absorption and unexplored carrier dynamics. Impurity ion doping offers a route to tune electrical conductivity and charge carrier transport. Herein, we synthesized Cu-doped Cs2AgBiBr6 (CABB) nanocrystals using a hot-injection approach and investigated the charge carrier's dynamics through ultrafast pump-probe spectroscopy. Copper introduction into the CABB lattice enhanced absorption in the near-infrared region and introduced sub-band gap defect states in CABB NCs. The transient absorption study revealed a faster bleach decay with increased copper doping, as a result of charge transfer from the conduction band to copper defect states. Also, an optical pump terahertz probe study displays higher photoconductivity and mobility in Cu-doped CABB NCs. Slower mobility decay in Cu-doped systems was attributed to the charge carrier's entrapment at the defect state. These findings suggest that copper-doped CABB is a superior contender for optoelectronic applications over conventional CABB.