Van der Waals heterostructures formed by inorganic perovskites and transition metal dichalcogenides (TMDCs) have promising applications in photonics and optoelectronics. However, there are few studies on the properties of CsPbBr3/TMDC at low temperatures. Here, we demonstrate van der Waals epitaxy of CsPbBr3 nanowires (NWs), nanoplates (NPs) and nanocones (NCs) on monolayer (ML) WSe2, and investigate the lattice dynamics of the heterostructure at low temperatures using temperature-dependent Raman spectroscopy. In addition, temperature-dependent photoluminescence (PL) spectroscopy shows that the type II band alignment between CsPbBr3 and ML WSe2 leads to a broad emission peak at the low-energy side of the ML WSe2 emission at low temperatures. Meanwhile, a high-energy peak appears near the CsPbBr3 emission below 133 K, which may be related to the phase transition of CsPbBr3 from the cubic to the orthorhombic phase. These findings are important for the development of van der Waals heterostructure based self-powered photodetector with high performance.
CsPbX3 (X = Cl, Br, and I) quantum dots (QDs) and Cu2+-doped CsPbCl3 QDs with different Cu-to-Pb molar ratios were synthesized via a solvent-based thermal synthesis method. The photoluminescence (PL) properties of these Cu2+-doped CsPbCl3 QDs were also investigated in this study. The results showed that with the increase in the Cl− concentration the surface defects of CsPb(Cl/Br)3 QDs increased, which resulted in an increase in the non-radiative recombination of excitons and weakened the PL intensity. Moreover, Cu2+-doped CsPbCl3 QDs maintained the cubic crystal structure of the initial phases. Owing to the doping of Cu2+ ions, the surface defects of CsPbCl3 QDs were effectively eliminated, which facilitated the excitonic recombination via a radiative pathway. The PL quantum yields (PLQYs) of Cu2+-doped CsPbCl3 QDs were increased to 51%, showing great photostability. From the results, it is believed that Cu:CsPbCl3 QDs can be widely used in optoelectronic devices.
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