Suppressing Auger Recombination of Perovskite Quantum Dots for Efficient Pure-Blue-Light-Emitting Diodes

Abstract

It is a big challenge to achieve pure-blue (≤470 nm) perovskite light-emitting diodes (PeLEDs) with high efficiency and stability. Here, we report pure-blue (electroluminescence at 469 nm) PeLEDs with a full width at halfmaximum of 21 nm, high external quantum efficiency of 10.3%, luminance of 12 060 cd m −2 , and continuous operation half-life of 25 h, representing the stateof-the-art performance. This design is based on strongly quantum confined CsPbBr 3 quantum dots (QDs) with suppression of Auger recombination, which was enabled by inorganic ligands, replacing initial organic ligands on the QDs. The inorganic ligand acts as a "capacitor" to alleviate the charge accumulation and reduce the exciton binding energy of the QDs, which suppresses the Auger recombination, resulting in much lower efficiency roll-off of PeLEDs. Thus, the devices maintain high efficiency (>10%) at high luminance (>2000 cd m −2 ), which is of considerable significance for the display application.

High Color-Purity and Efficient Pure-Blue Perovskite Light-Emitting Diodes Based on Strongly Confined Monodispersed Quantum Dots

“…In contrast, the EL color coordinates of the b-QDs-10 device remain close to the perimeter of the chromaticity diagram even at driving voltages of 9 V. The color purity is up to 97.3%, with no significant change (97.3% to 97.2%) at different voltages, demonstrating high color purity and a much more stable EL spectrum (Figure d). The more stable output of the b-QDs-10 devices is attributed to a lower defect density, which can improve operational stability. , …”

“…The more stable output of the b-QDs-10 devices is attributed to a lower defect density, which can improve operational stability. 7,47 The current density−voltage-luminance (J-V-L) curves of the LEDs are shown in Figure 4a. The brightness of the devices based on the b-QDs-2 decreases under a driving voltage higher than 7 V. In contrast, the devices based on b-QDs-10 maintain an ultrahigh brightness (∼10 000 cd m −2 ) even under a high driving voltage of 10 V, indicating excellent stability.…”

Tuning the energy transfer in Ruddlesden–Popper perovskites phases through isopropylammonium addition – towards efficient blue emitters

“…But for blue-emitting PeLEDs, the progress in efficiency has been lagging behind, although many efforts have been dedicated to improving these devices. 12–25 Recently, a record EQE of 17.9% has been reported by ligand manipulation in on-substrate synthesis of quantum dots. 26…”

“…27 These three approaches rely on the use of active layers of very different nature, namely: (i) 3D MHPs, 15,25,28 (ii) quasi-2D perovskites, 17,21,22,29,30 and (iii) nanocrystals based on 3D MHPs. 16,23,31…”

“…Therefore, to obtain PeLEDs with high EQE with this approach, a careful selection of the ligands is crucial and often challenging. 16,23,31…”