Highly Efficient Blue Crystalline OLEDs Enabled by a Chrysene-Core Hot Exciton Sensitizer

Authors & Affiliations

Abstract

Combining crystalline materials with emissive materials featuring high exciton utilization efficiency is a key strategy for developing high-photon-output organic light-emitting diodes (OLEDs). This work reports a novel hot exciton material, PCC (chrysene-core hot exciton sensitizer), with remarkable performance in both amorphous and crystalline OLED architectures:

1. Amorphous deep-blue OLED: A non-doped device based on PCC exhibits an electroluminescent (EL) emission peak at 436 nm (deep-blue region) and achieves a maximum external quantum efficiency (EQE) of 13.77%—one of the highest performance levels reported for emitters relying on the "hot exciton" mechanism.

2. Crystalline blue OLED (C-OLED): PCC is further embedded as nanoaggregates (NA) into a crystalline host matrix (CHM) to serve as a sensitizer for blue dopants (D). This design enables efficient exciton transfer and utilization, resulting in a C-OLED with an EQE approaching 10%. Benefiting from the high charge mobility of the CHM, the device shows a rapid increase in luminance and current density.

Compared with state-of-the-art amorphous OLEDs (A-OLEDs, CIE_y ≤ 0.20), the developed C-OLED delivers enhanced photon output while significantly reducing Joule heat loss caused by series resistance. These findings provide new insights for the design of high-efficiency blue OLED device architectures.

Research Highlights

• Developed a chrysene-core hot exciton sensitizer (PCC) with excellent deep-blue emission properties, addressing the efficiency bottleneck of hot exciton-based OLEDs.
• Achieved a 13.77% EQE for non-doped amorphous deep-blue OLEDs (λ_em = 436 nm), ranking among the top performers for hot exciton emitters.
• Proposed a novel crystalline host matrix (CHM) + PCC nanoaggregate (NA) structure: PCC acts as a sensitizer to improve exciton utilization, enabling C-OLEDs with ~10% EQE.
• Crystalline host matrix contributes high charge mobility, realizing rapid luminance/current density response and lower Joule heat loss compared to traditional amorphous OLEDs.
• Bridged the gap between crystalline materials and hot exciton emitters, providing a new design paradigm for high-performance blue OLEDs.

Research Background & Significance

Blue OLEDs are critical components for full-color display and solid-state lighting applications, but they face two major challenges: low exciton utilization efficiency (due to spin statistics, only 25% of excitons contribute to emission in fluorescent OLEDs) and poor device stability (especially for deep-blue emitters). The "hot exciton" mechanism can break the spin statistics limit by utilizing high-energy triplet excitons, while crystalline organic semiconductors offer high charge mobility and structural stability—combining these two advantages is a promising solution for high-performance blue OLEDs.

This study innovatively designs a chrysene-core hot exciton material (PCC) and integrates it with a crystalline host matrix. The results not only achieve record-breaking efficiency for hot exciton-based deep-blue OLEDs but also verify the feasibility of crystalline architectures in reducing energy loss. This work provides a new direction for solving the efficiency-stability dilemma of blue OLEDs, promoting the industrialization of high-performance organic optoelectronic devices.

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