OLED Exciplex Interlayer Layout to Reduce Efficiency Roll-Off
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing organic light emitting devices (OLEDs) using TADF technology face efficiency roll-off due to exciton concentration at the p-type and n-type host layer interface, and energy loss from direct exciton capture by dopants.
Innovation Solution
Incorporating a bipolar interlayer between the p-type and n-type host layers, with a fluorescent dopant positioned at a preset distance from the interlayer, to form a spatially separated exciplex that enhances exciton distribution and reduces energy loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a TADF type interface exciplex is used as a host to collect singlet excitons, then the internal quantum efficiency can achieve theoretical breakthrough, but efficiency roll-off occurs due to exciton concentration at the p-type and n-type host layer interface
Solution Approach 1:
The device is segmented into distinct functional regions: p-type host layer, n-type host layer, and interlayer. This segmentation separates the exciton generation region (at the interface) from the energy release region (dopant locations), preventing exciton concentration problems while maintaining high internal quantum efficiency through spatial distribution of functions
Solution Approach 2:
An interlayer is introduced as an intermediary component between the p-type and n-type host layers. This interlayer mediates the interaction between the two host layers, enabling controlled exciton generation while preventing excessive exciton concentration, thus resolving the efficiency roll-off problem
2Use of energy by moving object
If dopants are positioned close to the host layer interface to capture excitons, then energy transfer efficiency is improved, but direct exciton capture by dopants causes energy loss
Solution Approach 1:
The problem is solved by transitioning from a one-dimensional proximity-based energy transfer to a three-dimensional spatially distributed system. Dopants are positioned at specific distances from the interlayer in three-dimensional space, allowing energy transfer through the interlayer while avoiding direct contact that would cause energy loss
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
This configuration effectively reduces exciton quenching and efficiency roll-off by promoting reverse intersystem crossing and separating exciton generation and energy release regions, thereby improving the overall efficiency of the OLED.
Implementation Method 1
the p-type host layer and the n-type host layer are configured to form, together with the interlayer, a spatially separated exciplex under an action of driving voltage; and the fluorescent dopant is configured to absorb energy of singlet excitons generated by the exciplex to emit light
Implementation Method 2
Utilizing the TADF type interface exciplex as a host is a focus of the development of the third generation OLED technology, in which nearly 100% singlet excitons are collected and transferred to the dopants through the delayed fluorescent effect
Data Source
AI summary
Provided is an organic light emitting device, including a p-type host layer, an n-type host layer, and an interlayer disposed between the p-type host layer and the n-type host layer, wherein at least one of the p-type host layer and the n-type host layer includes a fluorescent dopant, and a preset distance is present between the fluorescent dopant and the interlayer; the p-type host layer and the n-type host layer are configured to form, together with the interlayer, a spatially separated exciplex under an action of driving voltage; and the fluorescent dopant is configured to absorb energy of singlet excitons generated by the exciplex to emit light.