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Subodh Mhaisalkar1 Nripan Mathews1 Tze Chien Sum1 Cesare Soci1 Tim White1

1, Nanyang Technological University, Singapore, , Singapore

Metal halide perovskites have emerged as the only solution-processable photovoltaic technology to outperform multicrystalline silicon, by virtue of its intrinsic properties such as large absorption coefficient, balanced charge carrier transport, highly crystalline film formation, weak exciton binding energies, and slow bimolecular recombination. Since 2014, perovskites have made strides in light-emitting applications with first demonstrations of amplified spontaneous emission and LEDs. However, low luminescence, poor efficiencies of the light-emitting diodes (LEDs), and complex preparation methods currently limit further progress towards applications.

The prospects for advancing device efficiencies are contingent upon exploring new perovskite compositions and structures. Lower-dimensionality layered perovskites formulations permit for band gaps and exciton binding energy tuning, carrier mobility facilitated by the inorganic moeities, with the organic moieties providing additional controls for stability, light harvesting, and intralayer charge transport. Nanocrystals is yet another variant in perovskites that promises to yield new opportunities in advancing device performance. By carefully controlling the reaction conditions such as temperature, solvent, and ligands, hybrid perovskites of morphologies ranging from 0D quantum dots to 3D single crystals; and sizes stretching 6 orders of magnitude can be prepared.

This presentation will show that the incorporation of alkylated bromide molecules into the framework of a fully inorganic 3D-perovskite film yields remarkable improvement in the photophysical and morphological properties. Another approach highlighted would be a mesoscopic film architecture of 3D self-assembled nanocrystals, coupled with of lead bromide perovskites platelets that enable high-performance light-emitting diodes. These strategies yield photoluminescence quantum yields of over 80% and intense luminance (>56,000 cd m−2) LEDs associated with efficiencies in excess of 57.6 cd A−1 with an external quantum efficiency above 13%. Challenges and opportunities relating to stability, and further improvement in performance will also be discussed, with emphasis on their optoelectronic properties and recombination dynamics. <div id="UMS_TOOLTIP" style="position: absolute; cursor: pointer; z-index: 2147483647; background-color: transparent; top: -100000px; left: -100000px; background-position: initial initial; background-repeat: initial initial;"> </div>

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