Light Detecting Element With Thick Active Layer And Optimized Electrode
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing light detecting elements face challenges in achieving high detection sensitivity characteristics due to the trade-off between dark current reduction and external quantum efficiency, as increasing the thickness of the active layer tends to decrease external quantum efficiency.
Innovation Solution
A light detecting element is designed with a thickness of the active layer of 800 nm or more, where the value obtained by subtracting the absolute value of the lowest unoccupied molecular orbital (LUMO) of the n-type semiconductor from the work function of the surface in contact with the negative electrode is set within a predetermined range of 0.0 to 0.5 eV, using p-type and n-type semiconductor materials, and optionally including an electron transport layer with metal oxides or hydroxides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the thickness of the active layer is increased, then the dark current is reduced, but the external quantum efficiency tends to decrease
Solution Approach 1:
The patent applies parameter changes by precisely controlling the work function of the negative electrode surface and the LUMO level of the n-type semiconductor material to achieve a specific energy level difference (0.0 to 0.5 eV). This energy level alignment optimizes electron extraction while maintaining high external quantum efficiency, resolving the contradiction between reducing dark current (which requires thicker layers) and maintaining efficiency.
Solution Approach 2:
The patent uses composite materials by combining p-type semiconductor material and n-type semiconductor material in the active layer, with specific attention to the energy level alignment at the negative electrode interface. This composite structure enables both dark current reduction through increased thickness and maintained external quantum efficiency through optimized material composition and energy level matching.
2Measurement precision
If the thickness of the active layer is increased to reduce dark current, then detection sensitivity improves, but external quantum efficiency decreases
Solution Approach 1:
The patent resolves this contradiction by changing the energy level parameters at the negative electrode interface. By controlling the work function of the negative electrode and the LUMO level of the n-type semiconductor to achieve a specific energy difference (0.0 to 0.5 eV), the patent enables thick active layers (800 nm or more) to maintain high external quantum efficiency while reducing dark current, thereby improving detection sensitivity without sacrificing efficiency.
3Reliability
If the work function of the negative electrode surface is adjusted to optimize electron extraction, then external quantum efficiency improves, but dark current may increase
Solution Approach 1:
The patent applies parameter changes by precisely controlling both the work function of the negative electrode surface and the LUMO level of the n-type semiconductor material. The key innovation is achieving a specific energy level difference (0.0 to 0.5 eV) between these two parameters, which simultaneously optimizes electron extraction for high external quantum efficiency and suppresses dark current, resolving the contradiction between these two opposing requirements.
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 allows for a reduced dark current and improved external quantum efficiency, maintaining high sensitivity characteristics even with increased active layer thickness.
Implementation Method 1
The active layer contains a p-type semiconductor material and an n-type semiconductor material
Implementation Method 2
The energy (hv) of light incident on the active layer generates electric charges (holes and electrons) in the active layer
Data Source
AI summary
This light detecting element has a reduced dark current and improved external quantum efficiency. The light detecting element includes a positive electrode, a negative electrode, and an active layer that is provided between said positive electrode and said negative electrode, and that contains a p-type semiconductor material and an n-type semiconductor material. The thickness of the active layer is at least 800 nm. The value obtained by subtracting the absolute value of the LUMO of the n-type semiconductor material from the work function of the surface in contact with the negative electrode side surface of the active layer is 0.0 to 0.5 eV. The absolute value of the LUMO of the n-type semiconductor material is 2.0 to 10.0 eV.