Photoelectric Conversion Element for Indoor Light Harvesting
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Solution Overview
Problem
Photoelectric conversion elements using low-molecular weight P-type organic materials exhibit low photoelectric conversion efficiency when utilizing indoor light sources like fluorescent lamps or LED lamps due to shallow HOMO levels and mismatched spectra.
Innovation Solution
A photoelectric conversion element is designed with a substrate, electrodes, and a photoelectric conversion layer comprising a specific organic material represented by General Formula (1) and a N-type semiconductor material, such as a fullerene derivative, to enhance efficiency, where R1 and R2 are alkyl groups, n is an integer from 1 to 3, X is a halogen atom, and m is 1 or 2, forming a bulk heterojunction for improved light absorption and charge transport.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional low-molecular weight P-type organic materials are used in photoelectric conversion elements, then the device structure can be simplified and manufactured easily, but the photoelectric conversion efficiency is low when using indoor light sources
Solution Approach 1:
The patent changes the chemical structure parameters of the P-type organic material by introducing specific substituents (R1 and R2 alkyl groups with 6-22 carbon atoms, halogen atoms X at positions 2 and/or 3, and controlling the number of rings n=1-3). These parameter changes optimize the HOMO level depth and light absorption spectrum to match indoor light sources, thereby improving photoelectric conversion efficiency while maintaining the simplicity of low-molecular weight materials for easy manufacture.
Solution Approach 2:
The patent creates a composite photoelectric conversion layer by combining the developed P-type organic material with N-type semiconductor materials. This composite structure forms a bulk heterojunction that enhances charge separation and transport, significantly improving photoelectric conversion efficiency while still using processable low-molecular weight materials that can be manufactured relatively easily.
2Use of energy by moving object
If conjugated polymer-based P-type organic semiconductors are used, then the material can absorb sunlight effectively, but the Voc is low due to shallow HOMO and the current value is low with fluorescent lamp or LED lamp light
Solution Approach 1:
The patent changes the HOMO level parameter by introducing electron-donating alkyl groups (R1 and R2 with 6-22 carbon atoms) and controlling the molecular structure (number of rings n=1-3, positions of halogen atoms X). These parameter changes deepen the HOMO level to increase Voc while maintaining good absorption of indoor light sources through appropriate spectral matching, thereby simultaneously improving both efficiency and reliability.
3Productivity
If materials are developed to match spectra of fluorescent lamps or LED lamps, then photoelectric conversion efficiency against indoor light can be improved, but the device complexity increases
Solution Approach 1:
The patent achieves spectral matching with indoor light sources by adjusting the molecular parameters of the P-type organic material, specifically the type and position of substituents (alkyl groups R1 and R2, halogen atoms X) and the core structure (number of rings n). This molecular-level parameter adjustment enables efficient absorption of fluorescent lamp and LED spectra without requiring complex device structures or additional components, thus improving photoelectric conversion efficiency while maintaining relatively simple device complexity.
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 element achieves high photoelectric conversion efficiency with weak indoor light, enabling effective power generation for IoT devices and extending battery life in devices without commercial power supplies.
Implementation Method 1
photoelectric conversion element capable of efficiently generating electric power with indoor light
Data Source
Figure 1~4
Figure 5~9
AI summary
A photoelectric conversion element including a substrate, a first electrode, an electron-transporting layer, a photoelectric conversion layer, a hole-transporting layer, and a second electrode, where the first electrode, the electron-transporting layer, the photoelectric conversion layer, the hole-transporting layer, and the second electrode are disposed on or above the substrate, wherein the photoelectric conversion layer includes an organic material represented by General Formula (1) below, and a N-type semiconductor material, where, in General Formula (1), R1 and R2 are each independently an alkyl group having 6 or more but 22 or less carbon atoms, n is each independently an integer of from 1 through 3, X is each independently a halogen atom, and m is each independently 1 or 2.