Organic Photosensitive Device Intermix Layer for Quantum Efficiency
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Solution Overview
Problem
Existing organic image sensors face issues with high dark current and low power conversion efficiency due to limitations in quantum efficiency when pixel size is reduced.
Innovation Solution
A photosensitive device with a donor-intermix-acceptor (PIN) structure is developed, incorporating organic hole transport and electron transport layers, an intermix layer, and electron blocking layers to enhance photocurrent and optical characteristics, using materials like P3HT and PCBM, and configurations such as P3HT:PCBM and PTB7:PC70BM to improve quantum efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pixel size is shrunk down to improve sensor integration, then device complexity is reduced and integration is improved, but quantum efficiency deteriorates leading to lower light sensing capability
Solution Approach 1:
The patent employs a composite organic photoactive layer combining electron-donating and electron-accepting materials (e.g., P3HT:PCBM bulk heterojunction) to create efficient charge separation pathways. This composite structure maintains high quantum efficiency in miniaturized pixels by optimizing the donor-acceptor interface for effective exciton dissociation, resolving the contradiction between small pixel size and light sensing capability.
Solution Approach 2:
The patent implements specialized electron-blocking and hole-transport layers with tailored material properties at specific device regions. These functional layers are strategically positioned to optimize charge carrier extraction and blocking locally, ensuring high quantum efficiency is maintained even when overall device dimensions are reduced for better integration.
2Ease of manufacture
If conventional organic materials are used in image sensors, then ease of manufacture is maintained, but dark current increases and power conversion efficiency decreases
Solution Approach 1:
The patent systematically optimizes material parameters including HOMO-LUMO energy levels, molecular weight, and side-chain structures of organic compounds. By carefully selecting and tuning these parameters, the invention achieves low dark current and high power conversion efficiency while maintaining compatibility with solution-processing manufacturing techniques for organic materials.
Solution Approach 2:
The patent uses composite organic photoactive layers with optimized donor-acceptor combinations (e.g., PTB7:PC71BM, P3HT:PCBM) that simultaneously achieve low dark current through effective charge separation and high power conversion efficiency through improved light harvesting, all while remaining compatible with standard organic material processing methods.
3Device complexity
If existing organic sensor structures are used, then device complexity is kept simple, but power conversion efficiency remains low
Solution Approach 1:
The patent segments the photoactive layer into distinct electron-donating and electron-accepting phases within a bulk heterojunction structure. This segmentation creates extensive donor-acceptor interfaces that facilitate efficient exciton dissociation and charge separation, significantly improving power conversion efficiency while maintaining a relatively simple single-layer device architecture that does not require complex multi-layer stacking.
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 solution significantly reduces dark current density and increases short-circuit current density and power conversion efficiency, achieving external quantum efficiency greater than 60% with adjustable optical characteristics.
Implementation Method 1
an organic photoactive layer disposed on the hole transport layer and comprising a mixture of an electron-donating material and an electron-accepting material
Implementation Method 2
comprising a mixture of an electron-donating material and an electron-accepting material, wherein the electron-donating material comprises a first organic compound and the electron-accepting material comprises a second organic compound
Data Source
AI summary
The present disclosure provides a photosensitive device. The photosensitive device includes a donor-intermix-acceptor (PIN) structure. The PIN structure includes an organic hole transport layer; an organic electron transport layer; and an intermix layer sandwiched between the hole transport organic material layer and the electron transport organic material layer. The intermix layer includes a mixture of an n-type organic material and a p-type organic material.