Optimization of power conversion efficiencies of organic photovoltaics by tuning of nanoscale morphology

2015 Fiscal Year Final Research Report

• Project/Area Number: 24750012
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Physical chemistry
• Research Institution: The University of Tokyo
• Principal Investigator: Fujii Mikiya 東京大学, 工学(系)研究科(研究院), 助教 (20582688)
• Project Period (FY): 2012-04-01 – 2016-03-31
• Keywords: 有機薄膜太陽電池 / 電子状態計算 / 電荷移動反応 / 非断熱化学反応

Outline of Final Research Achievements

The objective of this project is revealing a fine mechanism of organic photovoltaics and proposing an physical indicator to optimize their power conversion efficiencies (PCE). We performed ab initio calculation for the charge transfer reaction at the interface of electronic donor and acceptor molecules. As a result, pairs of donor and acceptor molecules that are used in high PCE photovoltaics exhibit largest photon-absorbing charge-bridging (PACB) states on both molecules, from which charge separation to free carriers should occur easily. Even if the main absorber of photons is the bulk donor, the charge-bridging states can enhance the charge-generation as additive photon-absorbers at the interface or intermediate states of the charge separation started from donor-excitons. PACB, therefore, leads to the highest short circuit current density and PCE．Finally, we also proposed analyzing photo-induced dipole moment which can be used as an indicator of strength of the PACB.

Free Research Field

理論化学・計算化学