Large reverse saturable absorption at sunlight power level using ultralong lifetime of triplet excitons

2016 Fiscal Year Final Research Report

• Project/Area Number: 26708010
• Research Category: Grant-in-Aid for Young Scientists (A)
• Allocation Type: Partial Multi-year Fund
• Research Field: Functional solid state chemistry
• Research Institution: Tokyo Institute of Technology
• Principal Investigator: Hirata Shuzo 東京工業大学, 物質理工学院, 助教 (20552227)
• Project Period (FY): 2014-04-01 – 2017-03-31
• Keywords: 三重項 / 非線形吸収 / 逆過飽和吸収 / 光制限効果 / オプティカルリミット / 室温りん光 / 多段階励起 / ステロイド

Outline of Final Research Achievements

Large reverse saturable absorption (RSA) at sunlight power level was observed from a host-guest amorphous material composed of d12-coronene as a guest and β-estradiol as a rigid amorphous host. Large highly symmetric two dimensional (2D) aromatic structure of d12-coronene doped into the rigid host causes ultralong triplet lifetime as well as high triplet yield, serving efficient accumulation of the triplet excitons of d12-coronene under weak excitation light. The high absorption coefficient of the triplet state (σ34) compared with that of the ground state (σ01) for d12-coronene is also caused by the highly symmetric 2D aromatic structure. The efficient accumulation of the triplet excitons and high σ34/σ01 led to an onset of the RSA characteristics under irradiance below 10-1 mW cm-2. An film of the amorphous material showed a large decrease of transmittance from 66% at 0.02 mW cm-2 to 24% at 50 mW cm-2 for continuous light at 405 nm.

Free Research Field

光物理化学