This was achieved by changing the surface energy via the removal of unreacted precursors - without causing the aggregation of the dots. showed that treating spin cast CsPbI 3 quantum dot films with methyl acetate stabilises the cubic structure. In contrast CsPbCl 3 and CsPbBr 3 quantum dots are phase-stable in the cubic polymorph over long periods, however CsPbI 3 will convert back to an orthorhombic configuration over a few days in ambient conditions. ![]() Due to the elevated temperature and the effect of reduced surface area, all CsPbX 3 nanocrystals crystallise into the cubic phase during synthesis. However, this phase only forms in bulk CsPbI 3 at temperatures above 300 ☌. The cubic phase is far more suitable for photovoltaic applications as a result of a narrower bandgap (1.73 eV). This result predated the synthesis of colloidal perovskite quantum dots, and the nanocrystals were instead formed through surface interactions when a mixture of methylammonium iodide and lead iodide was spin cast onto a TiO 2 surface.Īt room temperature, bulk CsPbI 3 forms an orthorhombic crystal lattice with a large bandgap of ~2.8 eV. The first use of perovskite quantum dots in solar cells was in 2011 by Im et al., where MaPbI 3 nanocrystals acted as a light-sensitiser in a structure resembling a dye-sensitised solar cell, with a power conversion efficiency of 6.5% reported. However, recent results suggest that perovskite quantum dots could play a role in future photovoltaic devices. This is likely due to the limited time that such materials have been available. Quantum Dot Solar CellsĬurrently, reports of perovskite quantum dot solar cells are still limited, especially when compared to bulk and 2-dimensional perovskites. Details on a selection of the applications that have been investigated are given below. Currently, the field is not well researched, but initial results are extremely promising. Perovskite quantum dots have huge potential for a range of applications in electronics, optoelectronics, and nanotechnology. Such perovskite nanocrystals are simple to synthesise in a colloidal suspension and are easily integrated into optoelectronic devices using readily available processing techniques, making them a strong contender for future technologies. Although defect and trap sites are present, their energies are positioned outside the bandgap and are either located within the conduction or valence bands. These quantum dots are highly tolerant to defects, as they require no passivation of the surface to retain their high PLQY. Recently, has been shown that reducing the dimensions of a perovskite crystal down to a few nanometres results in the creation of quantum dots with very high photoluminescence quantum yields and excellent colour purity (i.e., narrow emission linewidths of ~10 nm for blue emitters and 40 nm for red emitters ). ![]() These have already been shown to have properties rivalling or exceeding those of metal chalcogenide QDs.ĭue to their outstanding photovoltaic performance, perovskites are receiving significant attention from the research community. A new class of quantum dot is emerging based on perovskites.
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