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High Efficiency Non‐Doped White Organic Light Emitting Diodes Based on a Bilayer Interface‐Exciplex Structure
摘要： High efficiency non-doped blue and white organic light emitting diodes (OLEDs) are realized by using a bilayer interface-exciplex (i-Exc) structure. Since the neutral exciplex are formed at the interface, the interface charge accumulation is reduced, thereby suppressing exciton quenching in the device. With the i-Exc structure, a maximum external quantum efficiency (EQE) of 23.1% is achieved in the non-doped blue phosphorescent OLED. Moreover, the white emission can be obtained by inserting an ultrathin orange-red phosphorescent emitter into the blue devices. The charge trapping in the orange-red emitter can be suppressed by adjusting the position of the ultrathin orange-red emitting layer in the device, contributing to superior spectral stability. The WOLED achieves an EQE of 20.0% and exhibits a stable warm white emission. The Commission Internationale de l’Eclairage (CIE) coordinates of WOLED are (0.41, 0.40) at 5 V and slightly change to (0.40, 0.41) at 9 V.
关键词： interface-exciplex,PHOLED,WOLED,bilayer structure,ultrathin non-doped emitting layers
更新于2025-11-14 15:26:12
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Effects of the emission layer structure on the electroluminescence performance of the white organic light emitting diodes based on thermally activated delayed fluorescence emitters
摘要： White organic light emitting diodes (WOLED) employing blue, green and red thermally activated delayed fluorescence (TADF) emitters of DMAC-DPS(B), 4CzIPN(G) and 4CzTPN-Ph(R) are fabricated and the effects of the emission layer (EML) structure, including EML thickness and 4CzTPN-Ph(R) dopant concentration, on the electroluminescence (EL) performance of G/B, G/R/B and R:G/B are investigated. It is found that the WOLED with the simple EML structure of G(20nm)/B(10nm) demonstrates maximum power efficiency (PE) around 16 lm/w and color rendering index (CRI) of 81. Meanwhile, R:G/B EML exhibits better EL performance than that of G/R/B EML. Especially, striking high CRI of 90 together with maximum PE around 13 lm/w can be obtained for R(1wt%):G(20nm)/B(10nm) EML by meticulously modulation of EML thickness and 4CzTPN-Ph(R) dopant concentration, indicating the achievement of balance between EL efficiency and CRI for non-doped TADF emitter-based WOLED. Furthermore, the stacked EML of G(20nm)/R(0.1nm) and G(20nm)/R(0.1nm)/B(10nm) reveal much more serious obstruction of delayed fluorescence (DF) compared to mixed EML of R(1wt%):G(20nm) and R(1wt%):G(20nm)/B(10nm), implying more intensified quenching effects from the sandwiched 0.1nm 4CzTPN-Ph(R) layer which will lead to deterioration of EL performance. Different photoluminescence (PL) and transient PL decaying dynamics derived from the sandwiched 4CzTPN-Ph(R) ultrathin layer is found to be critical. The decaying dynamics responsible for such EML structure dependent EL performance is discussed in details.
关键词： WOLED,TADF,emission layer (EML),decaying dynamics
更新于2025-11-14 15:24:45
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Organic light-emitting diodes with split recombination zones: A concept for versatile color tuning
摘要： White organic light emitting diodes (WOLEDs) for general lighting applications are still mostly considered as a possibility rather than a definitive next step in solid-state lighting technology. Vacuum deposited WOLEDs usually run into troubles of complicated manufacturing processes, incompatible emitters, high-precision requirements for emitting layer structuring and monolithic integration. In this work we present a simple method of achieving white emission from a single-stack OLED with three (red, green and blue) emitters utilizing a laterally structured shadow mask. Only the green emitter is deposited via this mask without any alignment requirements, allowing the decoupling of recombination zones for achieving simultaneous emission from all emitters, circumventing the need of additional charge generating layers or vacuum-breaking structuring steps. A highly tunable white emission is demonstrated, irrespective of charge transporting systems or green emitters used. The resulting WOLEDs show external quantum efficiencies and luminous efficacies up to 14% and 26 lm/W, respectively, with CIE coordinates of (0.40, 0.40) and CRI values of up to 80.
关键词： TADF,WOLED,EQE,phosphorescence,recombination zone,OLED
更新于2025-09-16 10:30:52