Bipolar Organic Compound for OLED Luminous Efficiency
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Solution Overview
Problem
Current OLED technologies face limitations in luminous efficiency and cost due to the high production costs of phosphorescent materials and the inefficiencies of fluorescent and TTA materials, while TADF materials are scarce and do not meet device performance needs.
Innovation Solution
A bipolar compound with a phosphorus-oxygen five-membered ring structure is developed, which acts as an electron acceptor, balancing hole and electron transport, improving luminous efficiency and reducing production costs by using a phosphorus-oxygen group with high triplet energy levels for efficient light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If phosphorescent materials are used in OLED light-emitting layer, then internal quantum yield can reach 100%, but production cost is high and efficiency roll-off is serious
Solution Approach 1:
The patent replaces expensive phosphorescent materials containing heavy metals (Ir, Pt, Os, Re, Ru) with inexpensive TADF materials based on organic compounds. The TADF materials achieve high internal quantum yield (up to 100%) through reverse intersystem crossing mechanism without requiring rare metal elements, thus resolving the contradiction between high efficiency and low production cost
Solution Approach 2:
The patent modifies molecular structure parameters by designing specific TADF materials with small energy gaps between S1 and T1 states, and long triplet exciton lifetimes. These parameter changes enable efficient reverse intersystem crossing and high internal quantum yield while maintaining low material cost
2Ease of manufacture
If fluorescent materials are used in OLED light-emitting layer, then production cost is low, but internal quantum yield does not exceed 25%
Solution Approach 1:
The patent introduces TADF materials as an intermediary between fluorescent and phosphorescent materials. TADF materials use organic compounds like fluorescent materials (low cost) but achieve phosphorescent-level efficiency (100% internal quantum yield) through the reverse intersystem crossing mechanism, mediating the trade-off between cost and efficiency
3Use of energy by moving object
If TTA materials are used in OLED light-emitting layer, then internal quantum yield can reach 62.5%, but efficiency roll-off phenomenon is significant
Solution Approach 1:
The patent adopts TADF materials that utilize long-lived triplet excitons through reverse intersystem crossing, avoiding the efficiency roll-off problem of TTA materials. The long triplet exciton lifetime allows efficient charge recombination and high internal quantum yield without significant efficiency degradation under high current density
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The compound enhances luminous efficiency, reduces operating voltage, and increases the lifetime of OLED devices while enabling the emission of dark blue light with a shorter wavelength, offering a cost-effective solution for OLED devices.
Implementation Method 1
The singlet excited state S1 of fluorescent materials return to the ground state S0 through radiative transition
Implementation Method 2
phosphorescent materials can strengthen the intramolecular intersystem crossing through the spin coupling
Implementation Method 3
under certain temperature conditions, the reverse intersystem crossing (RISC) of the T1 state excitons may occur to achieve the T1→S1 process
Implementation Method 4
the electrons generated by the cathode will move, be injected into the hole transport layer and the electron transport layer, respectively, and then migrate to the light-emitting layer
Implementation Method 5
the holes generated by the anode and the electrons generated by the cathode will move, be injected into the hole transport layer and the electron transport layer, respectively
Implementation Method 6
T1 state excitons can up-switch to S1 state by absorbing environmental heat
Implementation Method 7
using a phosphorus-oxygen group with high triplet energy levels for efficient light emission
Data Source
AI summary
An organic compound has a structure as shown in Formula (I). The compound has a phosphorus-oxygen five-membered ring combined with a five-membered ring as an electron acceptor unit. The compound has a high luminous efficiency and a lower material cost than phosphorescent metal complexes. The compound can be built into a stack structure of organic optoelectronic device, such as OLED. The resultant organic optoelectronic device includes an anode, a cathode, and at least one organic thin film located between the anode and the cathode, the organic thin film contains the compound as shown in Formula (I).