Voltage‐Dependent Multicolor Electroluminescent Device Based on Halide Perovskite and Chalcogenide Quantum‐Dots Emitters

Abstract

Electroluminescent devices based on metal halide perovskites have attracted extensive attention owing to their high external quantum efficiency, excellent color purity, and inexpensive solution process. So far, extensive efforts have been made to improve the efficiency of the monochromatic perovskite light‐emitting diodes (LEDs). However, multicolor perovskite‐based LEDs are seldom studied. Here, an individual device capable of multicolor emission in response to the passage of external electric bias is demonstrated. With the rational design of the energy band alignment and control of the carrier transport property, color‐tunable electroluminescent devices based on inorganic halide perovskite and chalcogenide quantum‐dots are fabricated with a wide color tuning range, high color reversibility, and ultrafast color switching. The mechanism of chromaticity tuning is investigated and is explained by the shift of the exciton recombination zone with the driving voltage. The presented work will impact scientific communities by encouraging the manufacture of cost‐effective, high‐resolution, and full‐color displays and human‐centric lighting.

Unravelling the role of band‐offset landscape on the recombination zone dynamics in perovskite light‐emitting diodes

“…UPS measurement (Figure S1) demonstrates that the conduction and covalent band levels of our pristine CsPbBr 3 are ‐3.3 and ‐5.7 eV, respectively. The conduction and covalent band levels of CsPbBr 3 : AVAB are ‐3.2 and ‐5.6 eV, [ 12 ] which are in good accordance with those of pristine CsPbBr 3 . To probe the dynamics of the recombination zone, an emissive QDs layer is deposited on the perovskite EML surface as the sensing layer.…”

“…Here we neglect the possible foster energy transfer between the EML and sensing layer, according to our previous report. [ 12 ] For Device C with a poly‐TPD layer, photons emitted from the QDs sensing layer are overwhelming, which is because that excitons are predominately confined within the sensing layer due to the larger energy barrier for electrons injection and the hole conductive nature of poly‐TPD. In the case of device B, as mentioned above, at low voltage region, recombination mainly occurs within the perovskite EML due to large energy barrier for holes at the perovskite/blue QD interface.…”

“…[ 7 ] In addition, the color purity as well as the emission spectrum can also be greatly affected by the position of the recombination zone. [ 12 ] Therefore, it is necessary to systematically investigate the dynamics of the recombination zone in PeLEDs to get better understanding of the mechanism that determines the device performance and operational stability.…”

44.3: Enhancing the Performance and Stability of Sky‐bule Perovskite Light‐emitting Diodes with Guanidinium Thiocyanate Additive

“…Because of its high electron/hole mobility, high photoluminescence quantum yield, high color purity, and color tunability characteristics, it provides a fire-new opportunity for high-definition display and solid-state lighting. [1][2][3][4][5][6] In recent years, light-emitting diodes based on metal halide perovskite materials (PeLEDs) have developed rapidly. Over the last five years, the external quantum efficiencies (EQEs) of the near-infrared, red and green perovskite lightemitting devices have all exceeded 20%.…”

Bright Single-Layer Perovskite Host–Ionic Guest Light-Emitting Electrochemical Cells

“…Color tunability by voltage is an attractive function of LEDs and LECs, particularly guest/host systems. Voltage-tunable color can be achieved by multilayer structures, [30][31][32][33][34] blends involving metal complexes, [35][36][37] and OLED tandems [38][39][40] and a comparative table of their performance is shown in Table S2. Among these, LECs enable this color tuning functionality in a simple, single layer architecture.…”