Phosphonate/Phosphine Oxide Dyad Additive for Efficient Perovskite Light‐Emitting Diodes

Abstract

Additives play a critical role for efficient perovskite light‐emitting diodes (PeLEDs). Here, we report a novel phosphonate/phosphine oxide dyad molecular additive (PE‐TPPO), with unique dual roles of passivating defects and enhancing carrier radiative recombination, to boost the device efficiency of metal–halide perovskites. In addition to the defect passivation effect of the phosphine oxide group to enhance the photoluminescence intensity and homogeneity of perovskite film, the phosphonate group with strong electron affinity can capture the injected electrons to increase local carrier concentration and accelerate the carrier radiative recombination in the electroluminescence process. Owing to their synergistic enhancement on device efficiency, quasi‐two‐dimensional green PeLEDs modified by this dyad additive exhibit a maximum external quantum efficiency, current efficiency, and power efficiency of 25.1 %, 100.5 cd A−1, and 98.7 lm W−1, respectively, which are among the reported state‐of‐the‐art efficiencies.

Top-Down Exfoliation Process Constructing 2D/3D Heterojunction toward Ultrapure Blue Perovskite Light-Emitting Diodes

“…Furthermore, the recombination process was quantitatively analyzed by using the equations: PLQY = k r /(k r + k nr ) and τ average = (k r + k nr ) −1 , where k r and k nr represent the radiative and nonradiative composite rate constants, respectively. 38,39 As shown in Figure 3b, the increased k r signifies the enhanced radiative recombination process occurring within the 2D/3D perovskite film, which can be attributed to efficient energy transfer from the 2D phases to the emitting 3D phase.…”

“…Consequently, the photoluminescence quantum yield (PLQY) of the MeCN-sol treated perovskite film exhibits an enhancement to 56.1%, which is almost twice that of the pristine 3D perovskite film (Figure S14). Furthermore, the recombination process was quantitatively analyzed by using the equations: PLQY = k r /( k r + k nr ) and τ average = ( k r + k nr ) −1 , where k r and k nr represent the radiative and nonradiative composite rate constants, respectively. , As shown in Figure b, the increased k r signifies the enhanced radiative recombination process occurring within the 2D/3D perovskite film, which can be attributed to efficient energy transfer from the 2D phases to the emitting 3D phase. Conversely, the noteworthy decrease in k nr in the target perovskite film suggests a reduction in nonradiative energy losses, which originates from the effective defect passivation and suppressed exciton dissociation.…”

Modifying Low-Temperature-Annealed NiOx Nanoparticle Films for Improved Performance of Perovskite Light-Emitting Diodes

“…The diffraction peaks at 15 and 30.5° correspond to the (100) and (200) planes of the three-dimensional perovskite, and the peaks at around 5.4° correspond to the low-dimensional perovskite phases. The introduction of PSSNa enhances the intensity of the diffraction peaks, , suggesting that the perovskite films deposited on the PSSNa-modified NiO x films possess better crystallinity.…”

High-Performance All-Inorganic Architecture Perovskite Light-Emitting Diodes Based on Tens-of-Nanometers-Sized CsPbBr3 Emitters in a Carrier-Confined Heterostructure

“…We compared the device efficiency roll-off at high luminance with some of the state-of-the-art green PeLEDs employing nanostructured emitters, i.e., perovskite nanocrystals ,,− , or low-dimensional Ruddlesden–Popper perovskites ,,,,− as well as large-sized 3D emitters ,− (Table S1). Most green PeLEDs based on nanostructured emitters experience a significant decrease in EQEs at high brightness, with some losing over 50% efficiency at 50,000 cd m –2 , resulting in a maximum brightness of less than 100,000 cd m –2 .…”

“…The state-of-the-art approach to realizing high-efficiency green PeLEDs uses nanostructured emitters (crystal size less than 10 nm), such as perovskite nanocrystals ,− or low-dimensional Ruddlesden–Popper perovskites, ,− in which long-chain ligands are incorporated to impede crystal growth. Significant Auger recombination emerges when those devices are exposed to high current injection due to the concentrated local carrier density in the nanometer-sized luminescent centers.…”