Organolead halide perovskites, such as CH3NH3PbX3, are promising for applications including photovoltaics because of its excellent optoelectronic properties. Perovskite quantum dots (PQDs) are interesting due to their size-dependent properties and large surface area useful for surface functionalization. PQDs are also a good model system for understanding instability of perovskites, a major obstacle towards practical application. Recently, we have synthesized CH3NH3PbBr3 PQDs with narrow green photoluminescence (PL) using two different capping ligands, octylammonium bromide (OABr) and octadecylammonium bromide (ODABr). Transmission electron microscopy (TEM) determined that the average particle size is 3.9 ± 1.0 nm for PQDs-OABr and 6.5 ± 1.4 nm for PQDs-ODABr, respectively. The quantum yield (QY) of PQDs-OABr (~20%) was calculated to be twice the QY of PQDs-OABr (~10%), which is attributed to the better capping effect of OABr. Moreover, the exciton dynamics of PQDs were investigated using femtosecond transient absorption (TA) techniques, which revealed non-radiative recombination on the picosecond time scale mediated by surface trap states for both types of PQDs. The PL lifetime of the PQDs was measured by time-resolved photoluminescence (TRPL) spectroscopy to determine the radiative as well as non-radiative lifetimes on the nanosecond time scale. A model is proposed to explain the optical and dynamic properties of the PQDs with emphasis on major exciton relaxation or electron-hole recombination processes.

Synthesis, optical properties, and exciton dynamics of organolead bromide perovskite quantum dots

251st National Meeting (2016)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.