Thermodynamics-Induced Injection Enhanced Deep-Blue Perovskite Quantum Dot LEDs

Abstract

Precisely tuning emission spectra through the component control of mixed halides has been proved to be an efficient method for procuring deep-blue perovskite LEDs (PeLEDs). However, the inferior color instability and lifetime attenuation, originated from vacancy-and trap-mediated mechanisms under an external field, remain an uninterruptedly formidable challenge for the commercial development of PeLEDs. Here, an ultrafast thermodynamics-induced injection enhancement strategy was employed to promote efficient carrier recombination within perovskite quantum dots (QDs), accompanied by less inefficient charge accumulation and trap generation, enabling deep-blue PeLEDs with improved thermal and spectral stability. The resultant PeLEDs feature an external quantum efficiency (EQE) of 3.66%, a max luminance of 2100 cd/m 2 at the electroluminescence (EL) of 460 nm, and a halftime of 288 s. This work provides a general platform for promoting the EL performances and a deep insight into unraveling the degradation mechanism of blue PeLEDs.

Liquid Nitrogen Passivation for Deep-Blue Perovskite Quantum Dots with Nearly Unit Quantum Yield

“…Also, E b can be obtained from the temperature-dependent PL spectra to confirm the veracity of the above result E b from the absorption spectra. E b can be calculated using eq where I 0 is the maximum integrated intensity, E b is the exciton binding energy, and k B is the Boltzmann constant. , The fitted E b of LNP QDs is 232.1 meV from the temperature-dependent PL spectra in Figure b,c. However, the LNP-free QDs possessed a smaller value of E b (188.6 meV) in Figure S11 than that of LNP QDs, which is consistent with the logarithmic absorption spectra results.…”

Highly Efficient Pure‐Blue Perovskite Light‐Emitting Diode Leveraging CsPbBrxCl3−x/Cs4PbBrxCl6−x Nanocomposite Emissive Layer with Shallow Valence Band

“…Incorporation of Cl is a straightforward strategy to realize blue emission in perovskite materials. [8][9][10] Blue emissions can be obtained by simply adjusting the Cl ratio of the mixed halide (Br/Cl). However, because Cl vacancies are easily formed in the mixed halide (Br/Cl) perovskite system and can degrade the PLQY via defectmediated nonradiative recombination, it is pivotal to suppress Cl vacancies in highly luminescent blue-emitting perovskites.…”

Lattice strain modulation toward efficient blue perovskite light-emitting diodes

“…Although continuous bandgap tuning could be easily obtained, practical implementation of this strategy is largely hindered by the phase instabilities induced by the halide segregation and the decrease in the PLQY with increasing chloride content (13). Introducing quantum confinement effects represents the second strategy for blue emission, which can be achieved through either reduced structure dimensionality (2D or quasi-2D) (14,15) or decreased crystal size (nanocrystals) (16)(17)(18)(19)(20)(21). The quantum confinement approaches take advantage of large electron-hole (exciton) binding energy, which could largely increase the PLQY at low excitation intensity (22,23).…”