Comparative Study of Shelling CsPbBr₃ Quantum Dots with CdS and TiO₂

Halide perovskites (HP) have been attractive in the development of optoelectronics due to their many favorable properties, such as high efficiency and adjustable band gap. However, HP are unstable when exposed to an ambient atmosphere, including varying moisture, light, and heat, which limits their applications. Furthermore, HP quantum dots (QDs) have enhanced properties and improved stability compared to perovskite thin films because of the quantum effect. However, better stability is still desired for the introduction of HPQDs into optoelectronics. Shelling engineering is a powerful method that can boost the stability of nanomaterials. Nevertheless, it is still challenging to effectively shell HPQDs due to the harsh conditions required by the process. In this report, we will present the shelling of CsPbBr₃ QDs with titanium dioxide (TiO₂) and cadmium sulfide (CdS), respectively. The two shelling methods will be demonstrated in parallel with each of the protocols, structures, and properties of the products. Our results indicate that the shelling with CdS was successfully achieved, while the QDs collapsed during the shelling with TiO₂. Additionally, the photoluminescence of our HPQDs is dependent on the amount of CdS introduced during shelling. This research does not only demonstrate successful shelling of HPQDs with CdS, but also yields constructive insights for the shelling engineering of nanomaterials.