Strong Blue Emission from Sb 3+ -Doped Super Small CsPbBr 3 Nanocrystals

Teng

et al. 2020

Adv Funct Materials

Self Cite

The external quantum efficiencies (EQEs) of perovskite quantum dot lightemitting diodes (QD-LEDs) are close to the out-coupling efficiency limitation. However, these high-performance QD-LEDs still suffer from a serious issue of efficiency roll-off at high current density. More injected carriers produce photons less efficiently, strongly suggesting the variation of ratio between radiative and non-radiative recombination. An approach is proposed to balance the carrier distribution and achieve high EQE at high current density. The average interdot distance between QDs is reduced and this facilitates carrier transport in QD films and thus electrons and holes have a balanced distribution in QD layers. Such encouraging results augment the proportion of radiative recombination, make devices with peak EQE of 12.7%, and present a great device performance at high current density with an EQE roll-off of 11% at 500 mA cm −2 (the lowest roll-off known so far) where the EQE is still over 11%.their PL QYs. Diverse approaches have been proposed to boost the performance of QD-LEDs via surface passivation, [19] modification of carrier transport layer, [20][21][22] and anion exchange. [12] QD-LEDs have therefore demonstrated an impressive quick increase of peak external quantum efficiencies (EQEs) from 0.01% to 21.3% within 4 years, suggesting perovskite QDs as promising new-generation optoelectronic semiconductor materials. [6,7,12,21] In spite of the rapid development of perovskite QD-LEDs, at present, the EQEs of these devices tend to be acquired at low current density and manifest significant loss at higher current density, which is known as efficiency roll-off. In best-performed perovskite QD-LEDs, [12] the maximum EQE was obtained at a current density lower than 1 mA cm −2 ; when the current density reached 100 mA cm −2 , the EQE became only about 1%, indicating the efficiency loss reached 95%. Such efficiency loss actually limits achievable brightness and leads to excessive power consumption.Apart from perovskite QD-LEDs, perovskite film-LEDs present similar issues and recently, a few studies have come up with several methods to minimize EQE droop. Zou et al. and Yang et al. concluded that it was luminescence quenching caused by Auger recombination that was responsible for the efficiency roll-off. [23,24] To reduce carrier density in quantum wells (QWs), increased QW width was acquired via different

Section: Introductionmentioning

confidence: 99%

Low Roll‐Off Perovskite Quantum Dot Light‐Emitting Diodes Achieved by Augmenting Hole Mobility

Teng

et al. 2020

Adv Funct Materials

Self Cite

“…Some researchers have prepared leadfree (replacing Pb with tin [Sn], bismuth [Bi], germanium [Ge], indium [In], and antimony [Sb]) perovskite NCs to reduce their toxicity, but they do not realize a high PL QY. 177,266,[278][279][280] For example, Zhang et al recently realized the preparation of lead-free 2D (C 18 H 35 NH 3 ) 2 SnBr 4 perovskite NCs, and obtained PL QYs of 88% and 68% in colloidal suspension and in a film, respectively. Furthermore, the preparation of 350 cd/m 2 LEDs has been realized, which has significantly improved the application prospect of lead-free perovskite NCs in environmentally friendly solid-state lighting.…”

Section: Discussionmentioning

confidence: 99%

“…Another major problem for lead halide perovskite is the toxicity of Pb, which is also a stumbling block for its commercial applications. Some researchers have prepared lead‐free (replacing Pb with tin [Sn], bismuth [Bi], germanium [Ge], indium [In], and antimony [Sb]) perovskite NCs to reduce their toxicity, but they do not realize a high PL QY . For example, Zhang et al recently realized the preparation of lead‐free 2D (C 18 H 35 NH 3 ) 2 SnBr 4 perovskite NCs, and obtained PL QYs of 88% and 68% in colloidal suspension and in a film, respectively.…”

Section: Discussionmentioning

confidence: 99%

Metal halide perovskite nanocrystals and their applications in optoelectronic devices

et al. 2019

InfoMat

Self Cite

In recent years, metal halide perovskite nanocrystals (NCs) have been favored by many researchers due to their unique properties including long carrier diffusion length, high carrier mobility, tunable emission wavelength, and narrow full width at half maximum, making them great application potentials in optoelectronic devices. The photoluminescence quantum yields of perovskite NCs are nearly 100%, and the device efficiency of perovskite NC‐based light‐emitting diodes (LEDs) has been improved significantly from below 0.1% to over 20%. In addition, perovskite NC‐based solar cells and photodetectors have also developed rapidly in recent years. Here, we summarize the synthesis and the basic optoelectronic properties of metal halide perovskite NCs and introduce their applications in LEDs, solar cells, and photodetectors.

“…The initial increase in the relative PL intensity could be ascribed to the decrease in the defect concentration in the NCs during annealing. [58][59][60][61][62] The reduction of defects led to a decrease in the nonradiative recombination centers, enhancing PL intensity accordingly. For pristine CsPbI 3 NCs, only a slightly enhanced PL intensity was observable at 40°C.…”

Section: Samplesmentioning

confidence: 99%

Aluminum Distearate–Modified CsPbX ₃ (X = I, Br, or Cl/Br) Nanocrystals with Enhanced Optical and Structural Stabilities

Xue

et al. 2020

CCS Chem.

Cite this: CCS Chem. 2020, 2, 13-23Colloidal all-inorganic perovskite nanocrystals (PNCs), possessing unique optical properties, have attracted considerable attention in the field of semiconductor nanocrystals (NCs), but their application is hindered by the stability issue resulting partly from dynamic capping ligand binding. Herein, we report a simple method for the synthesis of all-inorganic cesium lead-based (CsPbX 3 ) NCs with enhanced structural stability and photoluminescence quantum yield. Aluminum distearate (AlDS) was introduced into the preparation of CsPbX 3 NCs, on the basis that the surface defects of CsPbX 3 NCs are passivated to form a protective layer on the CsPbX 3 NC surface simultaneously. Benefiting from surface modification, the resistance of the CsPbX 3 NC dispersion against ethanol, ultraviolet irradiation, and heat treatment was enhanced effectively. Moreover, the photoluminescence intensity and stability of the AlDS-modified NC-based films displayed functional superiority to those of pristine NC-based films.CsPbI 3 @Al-n NCs were synthesized by the hot-injection method reported in the literature 35,36 with minor modification. Briefly, 0.1628 g of Cs 2 CO 3 , 0.5 mL of OA, and Scheme 1 | Schematic illustration of the synthesis of CsPbX 3 @Al-n NCs and AlDS structure.