Introducing Ag Dopants into CdSe Nanoplatelets (NPLs) Leads to Effective Charge Separation for Better Photodetector Performance

Solution-processed colloidal cadmium chalcogenide nanoplatelets (NPLs)-based photodetectors (PD) are promising materials for next-generation optoelectronic devices due to their excellent optical properties. Here, we report on ultrafast carrier relaxation dynamics of four monolayer (4 ML) Ag-doped CdSe (Ag: CdSe) NPLs using ultrafast transient absorption spectroscopy and their photodetectors applications. A broad dopant emission is observed at around 650 nm with a large FWHM of ~431 meV and band edge emission at 515 nm. The intragap dopant state acts as a hole acceptor, which leads to better charge separation. The ultrafast transient absorption spectroscopy study shows faster carrier recombination dynamics with a hole transfer time scale of ~10 ps in Ag-doped CdSe NPLs. This supports the excited hole capture phenomenon at the dopant state. Ag-doped CdSe NPLs-based PD performed better than undoped CdSe NPLs with detectivity and responsivity values of 1.3×1010 Jones and 2.4 mA/W, respectively.

Transition Metal Ions Influence the Performance of Photodetector of Two-Dimensional CdS Nanoplatelets

Transition metal-doped two-dimensional (2D) semiconductor nanoplatelets (NPLs) with atomically precise thickness have attracted much research interest due to their inherent photo-physical properties. In this work, we have synthesized 2D Cu-doped CdS NPLs, investigated the charge transfer dynamics using ultrafast transient absorption spectroscopy, and fabricated an efficient photodetector device. A large Stoke's shifted emission at ~685 nm with an average lifetime of about ~1.45 μs is observed in Cu-doped CdS NPLs. Slower bleach recovery kinetics leads to large charge carrier separation in Cu-doped NPLs which is beneficial for photodetector applications. Cu-doped NPLs-based photodetectors exhibit high photocurrent, fast response (~120 ms), ~600 times higher photoresponsivity, and ~300 times higher detectivity (~4.1×1013 Jones) than undoped CdS NPLs. These excellent properties of Cu-doped CdS NPLs make this material an efficient alternative for next-generation optoelectronic devices.

A visible-light-active CuInSe2:Zn/g-C3N4/TiO2 nanowires for photoelectrocatalytic bactericidal effects

A visible-light-active CuInSe₂:Zn/g-C₃N₄/TiO₂ nanowire (NW) photoelectrode was prepared by in situ growth of g-C₃N₄ on the surface of TiO₂ NWs, followed by drop deposition of Zn-doped CuInSe₂ quantum dots (CuInSe₂:Zn QDs).

Synthesis of Ag/TiO2 nanocomposite via plasma liquid interactions: Improved performance as photoanode in dye-sensitized solar cell

Ag/TiO₂ nanocomposite was prepared by the atmospheric direct current plasma in aqueous solution to improve its performance in dye-sensitized solar cells (DSSCs) as the photoanode. The fabricated DSSC shows high power conversion efficiency over 6.5% and displays better long-term stability than that of referenced pure TiO₂. The comparison of photoluminescence spectra of Ag/TiO₂ and pure TiO₂ showed that only the Ag containing samples had notable photocurrent under visible light, which was attributed to the highly dispersed Ag, according to the EDS and XRD measurements. The short-circuit current density (Jsc) and open-circuit voltage (Voc) reached 13.43 mA cm^-2 and 0.72 V in Ag/TiO₂, and 9.44 mA cm^-2 and 0.68 V in pure TiO₂, respectively. The performance improvement in Ag/TiO₂ DSSC may occur due to the declined band-gap energy, retarded charge recombination and greater surface coverage of the sensitizing dye over Ag/TiO₂ nanocomposite.