Highly Efficient Light Emitting Diodes Based on In Situ Fabricated FAPbI₃ Nanocrystals: Solvent Effects of On‐Chip Crystallization

Abstract

The in situ fabricated perovskite nanocrystals (PNCs) obtained through spin‐coating a precursor solution are suitable candidates to achieve efficient perovskite light emitting diodes (PeLEDs). In this work, the solvent effects of on‐chip crystallization are investigated by correlating the nucleation and growth process of in situ fabricated formamidinium lead iodide (FAPbI3) nanocrystals with their optical and electronic properties. The FAPbI3 nanocrystals obtained from a precursor solution in γ‐butyrolactone (GBL) are smaller than those obtained from N,N‐dimethylformamide and dimethyl sulfoxide, and the relatively weak coordination between GBL and the precursor molecules enables reduced defect states in the resulted PNCs with enhanced photoluminescence properties. A modified LaMer model is proposed to describe the solvent effects in the on‐chip crystallization process. Based on these understandings, red emissive FA0.87Cs0.13PbI3 nanocrystal films with absolute photoluminescence quantum yields up to 70% are realized. Finally, an efficient PeLED with maximum luminance of 218 cd m−2 and peak external quantum efficiency of 15.8% is achieved with good reproducibility.

Polaron and Spin Dynamics in Organic–Inorganic Lead Halide Perovskite Nanocrystals

“…[ 7–11 ] Seminal demonstrations of defect tolerance include charge carrier lifetimes of ≈2 µs, long carrier diffusion lengths of ≈10 µm, and high photoluminescence (PL) quantum yield. [ 7,11–15 ] These attributes led to extremely efficient solution‐processed cost‐effective solar cells (>25%), low‐threshold lasing, and light‐emitting diodes. [ 2,5,12,16–21 ] Recently demonstrated hot phonon bottleneck helps to establish the potential for hot carrier photovoltaic devices that can break the single‐junction Shockley–Queisser limit for solar cells.…”

Dimension control of in situ fabricated CsPbClBr2 nanocrystal films toward efficient blue light-emitting diodes

“…erovskite light-emitting diodes (PeLEDs) are emerging as an alternative display technology due to their high color purity, high external quantum efficiency (EQE), and solution processability [1][2][3][4][5][6][7][8] . Benefiting from the ionic feature of the metal halide perovskite, PeLEDs can be directly fabricated through in situ fabrication technique by spin-coating perovskite precursor solution on targeting substrates [9][10][11][12][13][14] . Since the first report of room-temperature-operated perovskite-based electroluminescence (EL) devices in 2014 1 , the maximum EQEs of green, red, and near-infrared PeLEDs have exceeded 20%, which are comparable to organic light-emitting diodes and quantum dot light-emitting diodes [15][16][17][18][19][20][21][22] .…”

Organic‐Inorganic Hybrid Perovskite Nanomaterials: Synthesis and Application

“…In 2019, Zhong's group in suit fabricated FAPbI 3 via LARP, and focused on the solvent effects of on-chip crystallization. [54] As shown in Figure 5a, FAI, PbI 2 and DPPA-Br (3,3-diphenylpropylamine bromide) were dissolved in three solvents of DMF, GBL and DMSO respectively to prepare different precursor solutions, and then films were formed on the quartz substrate upon spin coating. After annealed, the samples based on GBL and DMF as solvents were observed with a dense and uniform surface, whereas the samples based on DMSO as a solvent was observed reveals lower surface coverage with obvious cracks and pinholes (Figure 5b-d).…”

“…However, due to the formation of PbCl 2 , the PLQY of FAPbCl 3 was extremely low, only about 2 %. In 2019, Zhong's group in suit fabricated FAPbI 3 via LARP, and focused on the solvent effects of on‐chip crystallization [54] . As shown in Figure 5a, FAI, PbI 2 and DPPA‐Br (3,3‐diphenylpropylamine bromide) were dissolved in three solvents of DMF, GBL and DMSO respectively to prepare different precursor solutions, and then films were formed on the quartz substrate upon spin coating.…”