Solid Solution of GaN and ZnO for Solar Absorption
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Solution Overview
Problem
Current photoexcitable materials, such as GaN and ZnO, have wide forbidden bands, limiting their ability to absorb solar energy efficiently, as they are primarily responsive to UV wavelengths, leaving a significant portion of the solar spectrum unused for energy conversion in applications like artificial photosynthesis and photocatalysis.
Innovation Solution
A solid solution of MN (where M is gallium, aluminum, or indium) and ZnO with a ZnO content of 30 to 70 mol % is developed, achieving a band gap energy of 2.20 eV or less, which narrows the forbidden band and enhances solar energy utilization by extending the absorption to longer wavelengths, utilizing nanoparticle deposition to form highly crystalline films at low temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wide band gap materials like GaN and ZnO are used, then material stability and UV responsiveness are improved, but solar energy absorption efficiency deteriorates due to limited absorption range
Solution Approach 1:
The patent creates a solid solution composite material by combining GaN and ZnO in specific ratios (30-70 mol% ZnO). This composite structure integrates the stability of both parent materials while achieving a reduced band gap of 2.20 eV or less, enabling broader solar spectrum absorption including visible light wavelengths that neither pure GaN nor ZnO can efficiently absorb alone.
Solution Approach 2:
The patent systematically varies the compositional parameters of the solid solution, specifically controlling the ZnO content between 30-70 mol%, to optimize the band gap energy to 2.20 eV or less. This parameter optimization allows the material to absorb photons with lower energy (longer wavelengths) while maintaining structural stability, thereby improving solar energy utilization efficiency.
2Use of energy by moving object
If band gap energy is reduced to extend absorption range, then solar energy utilization is improved, but material stability may deteriorate
Solution Approach 1:
The solid solution composite of GaN and ZnO maintains the wurtzite crystal structure characteristic of both parent materials, providing structural stability. The composite structure allows achieving a reduced band gap of 2.20 eV or less through compositional control (30-70 mol% ZnO) while preserving the crystalline stability needed for practical applications in solar energy conversion devices.
Solution Approach 2:
By precisely controlling the compositional parameter (ZnO content at 30-70 mol%) and resulting band gap energy (≤2.20 eV), the patent identifies an optimal parameter range where both solar energy utilization and material stability are satisfied. This parameter optimization ensures the material remains stable while achieving extended light absorption into the visible spectrum.
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 resulting photoexcitable material efficiently utilizes a broader range of solar energy, enhancing the efficiency of solar energy conversion in applications like hydrogen production and contaminant decomposition by reducing the forbidden band width, thereby improving the performance of photochemical electrodes.
Implementation Method 1
photoexcitable material includes: a solid solution of MN (where M is at least one of gallium, aluminum and indium) and ZnO, wherein the photoexcitable material includes 30 to 70 mol % ZnO and has a band gap energy of 2.20 eV or less
Data Source
AI summary
A photoexcitable material includes: a solid solution of MN (where M is at least one of gallium, aluminum and indium) and ZnO, wherein the photoexcitable material includes 30 to 70 mol % ZnO and has a band gap energy of 2.20 eV or less.