The development of highly efficient organic light-emitting devices (OLEDs) has long relied on heavy-metal-based phosphorescent materials to achieve near-100% internal quantum efficiency (IQE). However, the high cost and scarcity of precious metals have driven intense research into metal-free alternatives. Pure organic room-temperature phosphorescence (RTP) materials offer a promising path toward sustainable and cost-effective OLEDs. Despite their potential, practical application remains hindered by low photoluminescence quantum yields (PLQYs) in solid-state films—especially when directly used as emitters. To overcome this limitation, we introduce a novel strategy based on pure organic phosphor sensitization, where a phosphorescent molecule acts as an energy donor to transfer triplet excitons to a fluorescent emitter. This approach enables efficient harvesting of both singlet and triplet states without relying on heavy metals.
We selected benzimidazole-triazine derivative PIM-TRZ as the host material due to its intrinsic RTP capability, 2,6-di(phenothiazinyl)naphthalene (-DPTZN) as the phosphor sensitizer, and rubrene as the fluorescent emitter. The device architecture employed was ITO/NPB (30 nm)/TCTA (5 nm)/PIM-TRZ:10% DPTZN:X% Rubrene (20 nm)/TPBI (50 nm)/LiF (1 nm)/Al (100 nm), with varying rubrene doping levels (X = 0, 0.3, 0.5, 0.8, 1.0 wt%). The results demonstrated that device 2 with 0.3 wt% rubrene achieved a maximum external quantum efficiency (EQE) of 15.7%, luminance of 24,260 cd/m², power efficiency of 53.2 lm/W, and current efficiency of 47.6 cd/A. These values represent a significant advancement over conventional fluorescent OLEDs limited to 25% IQE.BMP-4 Protein Purity & Documentation
Photophysical studies revealed that Förster-type energy transfer from PIM-TRZ to -DPTZN is highly efficient, supported by strong spectral overlap and a calculated Förster radius of 29.6 nm. The transient photoluminescence data confirmed rapid decay lifetimes in the presence of rubrene, indicating effective energy migration from the host to the sensitizer and then to the fluorescent dopant.Prostein Antibody Cancer Moreover, the RTP nature of PIM-TRZ enhances intersystem crossing and stabilizes triplet states, facilitating Dexter-type energy transfer while minimizing non-radiative losses.PMID:34856161 Temperature-dependent PL measurements further confirmed the thermally activated phosphorescence behavior of PIM-TRZ, which plays a crucial role in sustaining triplet exciton populations.
Crucially, the use of a pure organic system avoids the need for rare-earth elements or transition metals, making this technology economically viable and environmentally friendly. The reported EQE of 15.7% approaches theoretical limits based on measured PLQYs and light out-coupling efficiency, demonstrating nearly complete utilization of triplet excitons. This work establishes a new paradigm for constructing high-performance OLEDs using classic fluorescence emitters through rational design of organic phosphor sensitization systems. It opens a pathway toward fully metal-free, high-efficiency electroluminescent devices with scalable and sustainable potential.MedChemExpress (MCE) offers a wide range of high-quality research chemicals and biochemicals (novel life-science reagents, reference compounds and natural compounds) for scientific use. We have professionally experienced and friendly staff to meet your needs. We are a competent and trustworthy partner for your research and scientific projects.Related websites: https://www.medchemexpress.com