Low-Temperature Photoluminescence Studies of different Cesium-based perovskite Quantum Dots

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Cesium lead halide perovskite quantum dots (CsPbX3 - QDs) have sparked a great deal of interest within research community due to their intrinsic and attractive photoluminescence properties that make them viable candidates for a wide range of applications in optoelectronics and nanotechnology. This study aims to investigate temperature-dependent photoluminescence (PL) properties over the 4 to 290 K temperature range using pre-synthesised perovskite quantum dot solutions with various halide compositions (CsPbBr3, CsPbBr2.7I0.3, CsPbBr1.5I1.5, and CsPbBrI2). With increasing temperature, the PL spectra peaks displayed a blue-shift for all CsPbX3 QDs samples. Additionally, the PL spectra exhibited the increased intensity and decreased width (FWHM) with decreasing temperature. The temperature dependence of FWHM was analysed using a linear coupling model indicating a strong exciton-phonon coupling. These findings are in accordance with previously reported results, indicating that all-inorganic colloidal CsPbX3 perovskite quantum dots are expected to have a promising future in the field of optoelectronic materials. Finally, A layer-by-layer deposition technique was used to fabricate CsPbX3 QD-based photovoltaic devices. The fabricated devices were characterised using J-V measurements, and a maximum power conversion efficiency of 0.67% was obtained in the case of CsPbBr2.7I0.3. Hindrance to charge transport due to the presence of long-chain insulating capping ligands on the QD surface is one of the major limiting factors for the use of perovskite QD in optoelectronic devices.