High-Efficiency Light-Emitting Diodes Based on Formamidinium Lead Bromide Nanocrystals and Solution Processed Transport Layers

Abstract

Perovskite nanocrystal light-emitting diodes (LEDs) employing architecture comprising a ZnO nanoparticles electrontransport layer and a conjugated polymer hole-transport layer have been fabricated. The obtained LEDs demonstrate a maximum externalquantum-efficiency of 6.04%, luminance of 12998 Cd/m 2 and stable electroluminescence at 519 nm. Importantly, such high efficiency and brightness have been achieved by employing solution processed transport layers, formamidinium lead bromide nanocrystals (CH(NH2)2PbBr3 NCs) synthesized at room-temperature and in air without the use of a Schlenk line, and a procedure based on atomic layer deposition to insolubilize the NC film. The obtained NCs show a photoluminescence quantum yield of 90% that is retained upon film fabrication. The results show that perovskite NC LEDs can achieve high-performance without the use of transport layers deposited through evaporation in ultra-high-vacuum.

Progress in halide-perovskite nanocrystals with near-unity photoluminescence quantum yield

“…Although the PLQY of PNCs using MeOAc and EtOAc is <70% (Figure 1B), these antisolvents are commonly chosen for a higher PNC product yield to facilitate their applications, especially in LEDs [55,56]. However, Konstantatos and coworkers [57] proposed a facile route to enhance the photophysical properties of FAPbBr 3 PNCs synthesized with short-chain capping ligands such as OctA and octanoic acid: simultaneous addition of OA and PbBr 2 to the redispersed material in toluene, prior to purification with MeOAc. The presence of OA removes the presence of PNC aggregates, while PbBr 2 provides an excess of Br − anions to passivate the halide defects and strengthen the ligand binding in the PNC surface [57,58].…”

“…However, Konstantatos and coworkers [57] proposed a facile route to enhance the photophysical properties of FAPbBr 3 PNCs synthesized with short-chain capping ligands such as OctA and octanoic acid: simultaneous addition of OA and PbBr 2 to the redispersed material in toluene, prior to purification with MeOAc. The presence of OA removes the presence of PNC aggregates, while PbBr 2 provides an excess of Br − anions to passivate the halide defects and strengthen the ligand binding in the PNC surface [57,58]. This procedure affords purified FAPbBr 3 PNCs with PL peak emission at 511 nm, FWHM = 22 nm, and PLQY around 90 ± 9% (Figure 1C).…”

Atomic layer deposition for quantum dots based devices

“…The remarkable enhancement of QDs could be attributed to complete passivation of the QDs surface states by the formation of Al-O bond network during the reactions between TMA and carboxylate/amino groups of the ligands (Fig. 2(b)) 75,91 . It was likely that the formed alumina on the surface successfully passivated the surface shallow defects, thereby enhancing the photoluminescence yield 103 .…”

Interface Engineering of CsPbBr3 Nanocrystal Light‐Emitting Diodes via Atomic Layer Deposition

“…After ALD trimethylaluminium (TMA) treatment, the PL intensity can be well kept, which implies that the stability tolerance of PNC to organic polar solvents was enhanced . It is proposed that the continuous TMA pulses applied to treat PNC thin films produce a crosslinking structure to defend the solvent erosion . Interestingly, other works showed that additional water pulses could suppress the PL decay of the PNC films .…”

“…As a self‐limitation gas‐phase surface chemical reaction, atomic layer deposition (ALD) can provide conformal and atomic‐level‐controlled thin‐film coating to keep PNC layers from the other solvents’ corrosion . After ALD trimethylaluminium (TMA) treatment, the PL intensity can be well kept, which implies that the stability tolerance of PNC to organic polar solvents was enhanced . It is proposed that the continuous TMA pulses applied to treat PNC thin films produce a crosslinking structure to defend the solvent erosion .…”