A polymer/small-molecule binary-blend hole transport layer for enhancing charge balance in blue perovskite light emitting diodes

Abstract

A polymer/small-molecule binary-blend hole transport layer provided balanced charge transport and efficient recombination of electrons and holes in the perovskite layer, and an optimal device based on the blended HTL shows the highest EQE of 5.30%.

Phosphine oxide modulator-ameliorated hole injection for blue perovskite light-emitting diodes

“…No obvious peak shift occurred in the PL emission of perovskite with different bottom layers, while the PL intensity was reduced with the increase in the TMFPPO ratio, which could be attributed to the carrier transfer from the EML to the HTL caused by the reduction in the energy barrier between the two layers. 40 Correspondingly, Fig. 2h exhibits the results of the time-correlated single photon counting measurements (TCSPC) for these samples, and the average PL lifetimes ( τ avg ) were determined through exponential decay fitting, 52 wherein the τ avg values of the perovskite on bare glass and PVK, 9 : 1, and 7 : 3 samples were 34.45, 20.05, 18.64, and 18.59 ns, respectively (Table S3†), which aligned well with the reduced PL intensity (Fig.…”

“…39 In our previous study, 2-(4-biphenyl)-5-(4- t -butyl-phenyl)-1,3,4-oxadiazole with its HOMO at −6.2 eV was blended with PVK to boost the hole injection, leading to an EQE of 4.53%. 40 However, there are still hole-injection barriers for going from the HTL to the perovskite EML in these works.…”

Near-Infrared LEDs Based on Quantum Cutting-Activated Electroluminescence of Ytterbium Ions

“…Although the PLQY of the CsPb­(Cl 0.90 Br 0.10 ) 3 :Yb 3+ PNC is higher than that of the CsPb­(Cl 0.82 Br 0.18 ) 3 :Yb 3+ PNC, the current density increased with the increased Br ratio before the radiation intensity reached the maximum value, demonstrating that the charge injection was boosted by the increased Br content. This result indicates that the charge injection balance plays the more important role than the PLQY of the EML. , Furthermore, the EL performance under different working voltages was investigated for the PNC LEDs based on CsPb­(Cl 0.82 Br 0.18 ) 3 :Yb 3+ (Figure d). The exciton and Yb 3+ NIR bands appear simultaneously and exhibit a similar growth trend as the voltage increases from 4.5 to 6.0 V (Figure S14), suggesting that the impact excitation by hot carriers did not contribute to the EL of Yb 3+ , otherwise the NIR intensity would increase more dramatically than that of the host due to the additional activation pathways of doping ions .…”

“…This result indicates that the charge injection balance plays the more important role than the PLQY of the EML. 69,70 Furthermore, the EL performance under different working voltages was investigated for the PNC LEDs based on CsPb(Cl 0.82 Br 0.18 ) 3 :Yb 3+ (Figure 4d). The exciton and Yb 3+ NIR bands appear simultaneously and exhibit a similar growth trend as the voltage increases from 4.5 to 6.0 V (Figure S14), suggesting that the impact excitation by hot carriers did not contribute to the EL of Yb 3+ , otherwise the NIR intensity would increase more dramatically than that of the host due to the additional activation pathways of doping ions.…”

Measurement and Model Evaluation of Solubility of 2-(4-tert-Butylphenyl)-5-(4-biphenyl)-1,3,4-oxadiazole in Different Organic Solvents at Various Temperatures

“…2-(4- tert -Butylphenyl)-5-(4-biphenyl)-1,3,4-oxadiazole (PBD) has been one of the most commonly used organic ETMs with good electron transfer performance in OLEDs. − The chemical structure of PBD is represented in Figure . However, when used in devices, the PBD layer was usually prepared by vacuum evaporation, which is time and energy consuming. − Along with the rapid development of solution processing technology for optoelectronic devices, the measurement and model evaluation of solubility data of PBD in various organic solvents are very important for printing PBD-based electron transport layers.…”