Creations of high-performance upconversion crystal systems and their scientific fundamentals based on molecular thermal engineering

2023 Fiscal Year Final Research Report

• Project/Area Number: 20H02082
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 19020:Thermal engineering-related
• Research Institution: Tokyo Institute of Technology
• Principal Investigator: Murakami Yoichi 東京工業大学, 科学技術創成研究院, 教授 (80526442)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 分子熱工学 / 光アップコンバージョン / 熱力学考究に基づく材料創製 / 結晶成長と分子混合の熱力学 / 三重項励起子の輸送現象

Outline of Final Research Achievements

In broad light-energy conversions including photocatalysts and photovoltaics, light with wavelengths longer than the material's threshold wavelength cannot be used in principle, which fundamentally limits their conversion efficiencies. This research is for photon upconversion (UC), which converts unused long-wavelength light into usable shorter-wavelength light. Most conventional UC materials are solutions in organic solvents and are flammable, volatile, and toxic, making them far from real applications. Additionally, it cannot be used in the presence of oxygen, has low efficiency, and requires high-intensity incident light. This research has completely resolved these problems, by creating a new concept of a binary solid-solution crystal formed by thermodynamic driving force; the developed materials can be used in the air, and it can be used with irradiation light of lower intensity than sunlight. We have created a revolutionary crystalline material system that efficiently performs UC.

Free Research Field

分子熱工学

Academic Significance and Societal Importance of the Research Achievements

上述のように、未利用な太陽光の長波長部分を利用可能なより短波長光に変換するUCについて従来想像し得なかった革命的な材料系を創出した。学術的には、(i)熱力学的な駆動力により形成される二成分固溶体結晶という独自の新概念を実証したこと、(ii)温度勾配制御を用いて基板上への固溶体多結晶膜生成を実現したこと、(iii)固溶体結晶中では励起子輸送が促進されることを実証したこと、(iv)多数の論文成果を産み出したこと、社会的には、(i)太陽光エネルギーの利用効率の向上を行う現実性のある高性能手段を創出したこと、(ii)国内企業との共同研究開始により社会実装に向けた動きを開始したこと、が意義となっている。