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Nanoplatelet Modulation in 2D/3D Perovskite Targeting Efficient Light-Emitting Diodes

Tian Wu, Yingguo Yang, Yatao Zou, Yusheng Wang, Chen Wu, Yujie Han, Tao Song, Qiao Zhang, Xingyu Gao, Baoquan Sun

Nanoscale. 2018 Nov 7;10(41):19322-19329.

PMID: 30324959

Abstract:

Light-emitting diodes (LEDs) based on two-dimensional (2D) perovskite nanoplatelets exhibit high electroluminescence (EL) efficiency because of the quantum confinement effect, which increases electron-hole recombination to promote radiative emission. It is well-known that a 2D nanoplatelet structure (〈n〉 = 1) is detrimental for luminescence efficiency due to possible thermal quenching of excitons at room temperature. Here, a simple strategy is developed to suppress growth of NMA2PbBr4 (〈n〉 = 1) nanoplatelets by carefully tuning the precursor ratio of cesium bromide (CsBr), formamidinium bromide (FABr) and 1-naphthylmethylammonium bromide (NMABr). The sub-domain size of the perovskite crystal decreases as the long-chain ligand NMABr ratio increases, leading to enhanced photoluminescence quantum yields (PLQY) due to size confinement effect when the NMABr ratio is below 60%. Unfortunately, the NMA2PbBr4 component in 2D/3D perovskites also grows with increasing NMABr ratio, which results in poor EL efficiency. FABr incorporation can provide additional control over suppression of NMA2PbBr4 growth in 2D/3D perovskites. A compact and uniform perovskite film with reduced NMA2PbBr4 content achieves PLQY of ∼61%. Benefiting from these features, a green perovskite LED yields current efficiency of 46.8 cd A-1 with an external quantum efficiency of 14.9%. This study paves a new way to modulate the crystal structure in perovskites via a simple and effective method for high-performance LEDs.

Chemicals Related in the Paper:

Catalog Number Product Name Structure CAS Number Price
AP7787691 Cesium bromide Cesium bromide 7787-69-1 Price
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