A Nanohybrid Containing Cyan-Emitting Copper Nanoclusters and TiO₂ Nanoparticles: Tuning of Optoelectronic Properties

Nanohybrid materials are designed to cover up the weaknesses of individual components. In this current work, an environment-friendly synthesis was used to produce a cyan-emitting copper nanocluster (Cu NC) with a quantum yield of 8.7 %. This negatively charged nanocluster was successfully used to make a nanohybrid with anatase titanium dioxide mesoporous nanoparticles having Lewis-acidic pores. The nanohybrid formation was characterized by time-correlated single-photon counting studies (TCSPC), solid-state UV-visible absorption spectroscopy and valence band X-ray photoelectron spectroscopy. A systematic increase of Cu NC loading on the TiO₂ showed an increase of current from a range of 10⁻⁷ A (in native TiO₂) to 10⁻⁴ A (1 : 10 Cu NC-TiO₂ hybrid). Interestingly, the photocurrent response of TiO₂ also dramatically improved from 8.9×10⁻³ mA to 4.1 mA in1 : 10 Cu NC−TiO₂ hybrid. Systematic variation of their weight ratio vividly demonstrated that 10 % w/w TiO₂−Cu NC hybrid was the most effective current generator, keeping the semiconducting and photovoltaic nature intact. The increase in photocurrent can be attributed to the long-lived electron-hole separation in the nanohybrid system.