Abstract
Emission color controlled, high quantum yield CH3NH3PbBr3 perovskite quantum dots are obtained by changing the temperature of a bad solvent during synthesis. The products for temperatures between 0 and 60 °C have good spectral purity with narrow emission line widths of 28-36 nm, high absolute emission quantum yields of 74% to 93%, and short radiative lifetimes of 13-27 ns.
Highlights
Nanometer-sized II–VI, III–V, and IV–VI semiconductor particles with size- and surface-dependent properties, often termed as colloidal quantum dots (QDs), have been extensively studied for more than 30 years,[1] with a variety of applications explored such as in photovoltaics, biosensors, light emitting diodes (LEDs), and so on.[2]
CH3NH3PbX3 perovskite nanoparticles were first explored as components of mesoporous titania based solar cells in 2009.[10]. But not until 2012 was high luminescence attributable to such nanoparticles observed in mesoporous material, in that case synthesized by a template method.[21]
Pérez-Prieto and coworkers used the capacity of medium length alkyl chain organic ammonium cations to produce colloidal perovskite QDs of 6 nm in diameter with ≈20% emission quantum yield (QY).[22]
Summary
In this Communication, we demonstrate the size-tunability of the bandgap of narrow size dispersion CH3NH3PbBr3 perovskite QDs (PQDs) by using temperature to exert control over the ligand-assisted reprecipitation process. The PQD samples have a small 10–20 nm Stokes shift between the absorption edge and the emission peak (Figure 1c) which is consistent with a direct exciton recombination process
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