Kinetics of primary processes in the organic solar cells by transient absorption and emission spectroscopies

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K05760
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Physical chemistry
• Research Institution: Josai University
• Principal Investigator: Mitsuke Koichiro 城西大学, 理学部, 教授 (50190682)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 有機太陽電池 / 光エネルギー変換 / 発光スペクトル / 時間分解分光 / 色素増感太陽電池 / ペロブスカイト太陽電池 / 酸化チタンナノ粒子 / 励起分子動力学

Outline of Final Research Achievements

We studied dye-sensitized solar cells (DSSCs) consisting of multilayered nanocrystalline TiO2 films with sensitizer dye to achieve economical photovoltaics with high power conversion efficiencies and better durability. The best fitting of the current-voltage curve to the theoretical equation allowed us to evaluate the series resistor RS, which values agree well with those derived from electrochemical impedance spectroscopy. Our results certified the validity of the equivalent circuit employed and the individual resistances obtained from EIS.
Ultrafast electron injection favorably proceeds from photoexcited dye molecule to TiO2 for the primary photovoltaic process in the DSSC. This electron injection should compete with other decays such as fluorescence emission or intramolecular nonradiative transitions. We estimated the rate constants for respective pathways from push-pull type organic dyes and compared the fluorescence lifetimes of dyes between isolated and adsorbed species.

Free Research Field

反応物理化学

Academic Significance and Societal Importance of the Research Achievements

軽量で低コストの色素増感太陽電池（DSSC）とペロブスカイト太陽電池（PVSC）は典型的なメゾスコピック太陽電池であり、フレキシブル基板の併用による住宅建材やモバイル機器への応用が期待されている。本研究成果により（１）内部電力損失の少ない長寿命のDSSCの製作、および（２）鉛フリーで色彩可変のPVSCの開発という目標に向けて、面積が約 0.25 cm2でエネルギー変換効率が約 10%のセルの安定供給、分子レベルでの発電機構の解明、およびレーザーと電子顕微鏡を用いた評価技術の確立への道筋が拓かれた。とくに、電子や励起子の生成、輸送、消滅現象に対する高速光検出よるアプローチが確立された。