Reduced Efficiency Roll‐Off and Improved Stability of Mixed 2D/3D Perovskite Light Emitting Diodes by Balancing Charge Injection

Fakharuddin, Azhar; Qiu, Weiming; Croes, Guillaume; Devižis, Andrius; Gegevičius, Rokas; Vakhnin, A.; Rolin, Cédric; Genoe, Jan; Gehlhaar, Robert; Kadashchuk, A.; Gulbinas, Vidmantas; Heremans, Paul

doi:10.1002/adfm.201904101

Cited by 116 publications

(134 citation statements)

References 50 publications

Supporting

Mentioning

124

Contrasting

Order By: Relevance

“…In addition, the co‐HTLs‐structure‐based device shows acceptable spectral stability when the applied voltage increases from 3.2 to 6.2 V (Figure f). Notably, our device exhibits low efficiency roll‐off, indicating a balanced charge injection and recombination . It is worth emphasizing that the stability of the EL spectra is mainly attributed to the balanced charge injection resulting from the co‐HTLs structure, as K + ‐based single HTL device undergoes phase segregation under constant voltage (Figure S13, Supporting Information).…”

Section: Resultsmentioning

confidence: 85%

“…Notably, our device exhibits low efficiency roll-off, indicating a balanced charge injection and recombination. [47] It is worth emphasizing that the stability of the EL spectra is mainly attributed to the balanced charge injection resulting from the co-HTLs structure, [17,48] as K + -based single HTL device undergoes phase segregation under constant voltage ( Figure S13, Supporting Information). Furthermore, through optimizing the device structure, the optimized blue perovskite NC-LED achieves a state-of-the-art EQE among the blue PeLEDs based on NCs.…”

Section: Device Performancementioning

confidence: 99%

See 1 more Smart Citation

Efficient and Spectrally Stable Blue Perovskite Light‐Emitting Diodes Based on Potassium Passivated Nanocrystals

Yang

Chen

Zhang

et al. 2020

Adv Funct Materials

157

155

View full text Add to dashboard Cite

Metal halide perovskites have aroused tremendous interest in the past several years for their promising applications in display and lighting. However, the development of blue perovskite light‐emitting diodes (PeLEDs) still lags far behind that of their green and red cousins due to the difficulty in obtaining high‐quality blue perovskite emissive layers. In this study, a simple approach is conceived to improve the emission and electrical properties of blue perovskites. By introducing an alkali metal ion to occupy some sites of peripheral suspended organic ligands, the nonradiative recombination is suppressed, and, consequently, blue CsPb(Br/Cl)3 nanocrystals with a high photoluminescence quantum efficiency of 38.4% are obtained. The introduced K+ acts as a new type of metal ligand, which not only suppresses nonradiative pathways but also improves the charge carrier transport of the perovskite nanocrystals. With further engineering of the device structure to balance the charge injection rate, a spectrally stable and efficient blue PeLED with a maximum external quantum efficiency of 1.96% at the emission peak of 477 nm is fabricated.

show abstract

Section: Resultsmentioning

confidence: 85%

Section: Device Performancementioning

confidence: 99%

Efficient and Spectrally Stable Blue Perovskite Light‐Emitting Diodes Based on Potassium Passivated Nanocrystals

Yang

Chen

Zhang

et al. 2020

Adv Funct Materials

157

155

View full text Add to dashboard Cite

show abstract

“…To understand the role of Auger recombination and spatial carrier distribution qualitatively, recombination rate R ( n ) can be divided into three components: trap‐assisted non‐radiative recombination ( An ), radiative recombination ( Bn 2 ), and Auger recombination ( Cn 3 ) (Equation (2), where A , B , and C are coefficients): [ 25,28,40,41 ]

R (n) = A n + B n^{2} + C n^{3}

…”

Section: Resultsmentioning

confidence: 99%

“…[ 23,24 ] To reduce carrier density in quantum wells (QWs), increased QW width was acquired via different methods like adjusting precursor ratios or partial cation exchange. Fakharuddin et al found 2D/3D mixed perovskite structure improved the carrier spatial distribution in the perovskite layer with the support of electroluminescent (EL) transients, [ 25 ] and stable EQE was achieved with the current density from 0.1 to 200 mA cm −2 . These studies point out that in perovskite LEDs, carrier density and carrier spatial distribution in emissive layer have great influences on the roll‐off behaviors of the devices.…”

Section: Introductionmentioning

confidence: 99%

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

Wang

Teng

et al. 2020

Adv Funct Materials

View full text Add to dashboard 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

show abstract

“…92 Heremans, Gulbinas, Fakharuddin, and coworkers showed that balanced electron and hole injection reduced the roll-off issue. 93 The exact mechanism responsible for the EQE roll-off is still under debate and needs more research works.…”

Section: Working Stabilitymentioning

confidence: 99%

Organic additive engineering toward efficient perovskite light‐emitting diodes

Liu

Ono

2020

InfoMat

View full text Add to dashboard Cite

Perovskite materials with excellent optical and electrical properties are promising for light‐emitting diodes. In the field of perovskite light‐emitting diodes (PeLEDs), organic materials additive engineering has been proved to be an effective scheme for enhancing efficiency and stability in PeLEDs. Most impressively, the reported external quantum efficiency of PeLEDs based on perovskite‐organic composite has reached over 20%. Herein, we will review the important progress of the organic materials' additive‐modified PeLEDs and discuss the remaining problems and challenges and the key research direction in the near future.

show abstract

Reduced Efficiency Roll‐Off and Improved Stability of Mixed 2D/3D Perovskite Light Emitting Diodes by Balancing Charge Injection

Cited by 116 publications

References 50 publications

Efficient and Spectrally Stable Blue Perovskite Light‐Emitting Diodes Based on Potassium Passivated Nanocrystals

Efficient and Spectrally Stable Blue Perovskite Light‐Emitting Diodes Based on Potassium Passivated Nanocrystals

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

Organic additive engineering toward efficient perovskite light‐emitting diodes

Contact Info

Product

Resources

About