Efficient charge generation at low energy losses in organic solar cells: a key issues review
- 6 May 2020
- journal article
- review article
- Published by IOP Publishing in Reports on Progress in Physics
- Vol. 83 (8), 082601
- https://doi.org/10.1088/1361-6633/ab90cf
Abstract
Light absorption generates strongly bound excitons in organic solar cells (OSCs). To obtain efficient charge generation, a large driving force is required, which causes a large energy loss (Eloss) and severely hinders the improvement in the power conversion efficiencies (PCEs) of OSCs. Recently, the development of non-fullerene OSCs has seen great success, and the resulting OSCs can yield highly efficient charge generation with a negligible driving force, which raises a fundamental question about how the excitons split into free charges. From a chemical structure perspective, the molecular electrostatic potential differences between donors and acceptors may play a critical role in facilitating charge separation. Although the Eloss caused by charge generation has been suppressed, charge recombination, particularly via non-radiative pathways, severely limits further improvements in the PCEs. In OSCs with negligible driving forces, the lowest excited state, a hybrid local exciton-charge transfer state, is believed to have a strong association with the non-radiative Eloss. This review discusses the efficient charge generation at low Eloss values in highly efficient OSCs and highlights the issues that should be tackled to further improve the PCEs to new levels (~ 20%).Keywords
Funding Information
- Beijing National Laboratory for Molecular Sciences (BNLMS-CXXM-201903)
- National Natural Science Foundation of China (21805287 21835006 51673201 51961135)
- National Key Research and Development Program of China (2019YFA0705900)
- Youth Innovation Promotion Association of the Chinese Academy of Sciences (2018043)
- Basic and Applied Basic Research Major Program of Guangdong Province (2019B030302007)
This publication has 89 references indexed in Scilit:
- Alkyl Chain Tuning of Small Molecule Acceptors for Efficient Organic Solar CellsJoule, 2019
- Wide-gap non-fullerene acceptor enabling high-performance organic photovoltaic cells for indoor applicationsNature Energy, 2019
- Single-Junction Organic Solar Cell with over 15% Efficiency Using Fused-Ring Acceptor with Electron-Deficient CoreJoule, 2019
- Fine-tuning of the chemical structure of photoactive materials for highly efficient organic photovoltaicsNature Energy, 2018
- Design rules for minimizing voltage losses in high-efficiency organic solar cellsNature Materials, 2018
- Material insights and challenges for non-fullerene organic solar cells based on small molecular acceptorsNature Energy, 2018
- Organic Photovoltaics over Three DecadesAdvanced Materials, 2018
- Quantitative relations between interaction parameter, miscibility and function in organic solar cellsNature Materials, 2018
- Flexible and Semitransparent Organic Solar CellsAdvanced Energy Materials, 2017
- 25th Anniversary Article: Bulk Heterojunction Solar Cells: Understanding the Mechanism of OperationAdvanced Materials, 2013