High-Performance Organic Solar Cells

High-Performance Organic Solar Cells

Author: Angewandte Chemie International Edition

The photovoltaic performance of organic solar cells has significantly improved in recent years. Cells based on fused-ring electron acceptors (FREAs), for example, have improved the power conversion efficiency of organic solar cells to 16 %. However, the synthesis of FREAs is usually complicated and expensive due to their multi-ring-fused core unit, which limits their commercial application. Simpler and cheaper electron acceptors, e.g., non-fused ring acceptors, could solve this issue.

Yahui Liu, Qingdao University, China, Zhishan Bo, Qingdao University and Beijing Normal University, China, and colleagues have developed an efficient design for high-performance fully non-fused ring acceptors. The team synthesized two acceptors, o-4TBC-2F and m-4TBC-2F (pictured below). Compared with typical FREAs, the syntheses of non-fused ring acceptors avoids ring-closing reactions that usually result in low yields, which makes the preparation of the acceptors simple and cost-effective.

 

By changing the location of alkyloxy side chains, the researchers can control the molecular structure and the aggregation behavior. The non-fused ring acceptor o-4TBC-2F with ortho-hexyloxy side chains has a planar backbone, while m-4TBC-2F has a twisted backbone. The planar structure of the ortho-substituted variant leads to higher crystallinity and facilitates intermolecular π-π interactions and charge transport. A power conversion efficiency of 10.26 % is obtained for devices based on o-4TBC-2F, which is one of the highest values for fully non-fused electron acceptors.


 

 

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