Donghui Li

Bio: Donghui Li is an academic researcher from Wuhan University of Technology. The author has contributed to research in topics: Organic solar cell & Materials science. The author has an hindex of 11, co-authored 27 publications receiving 306 citations.

Aggregation of non-fullerene acceptors in organic solar cells

Abstract: Organic solar cells (OSCs) employing non-fullerene acceptors (NFAs) have drawn significant research attention in recent years. Molecular stacking and aggregation of electron donors and acceptors within the photoactive layer is vitally important for light absorption and the photon-to-electricity conversion process. Herein, we present the versatile molecular stacking of the state-of-the-art NFAs, as well as the affecting factors including the chemical structures of NFAs and physical processing conditions. We highlight in particular experimental approaches to regulate molecular stacking and aggregation and summarize the influences of these features on optoelectronic and photovoltaic properties of NFA-based OSCs, which provide crucial guidance for further development of high performance OSCs.

13.9% Efficiency Ternary Nonfullerene Organic Solar Cells Featuring Low-Structural Order

Abstract: The insufficient phase separation between polymer donors and nonfullerene acceptors (NFAs) featuring low structural order disrupts efficient charge transport and increases charge recombination, con...

Influences of non-fullerene acceptor fluorination on three-dimensional morphology and photovoltaic properties of organic solar cells

Abstract: Fluorination of conjugated molecules has been established as an effective structural modification strategy to influence properties and has attracted extensive attention in organic solar cells (OSCs...

Graphdiyne Derivative as Multifunctional Solid Additive in Binary Organic Solar Cells with 17.3% Efficiency and High Reproductivity

Abstract: Morphology tuning of the blend film in organic solar cells (OSCs) is a key approach to improve device efficiencies. Among various strategies, solid additive is proposed as a simple and new way to enable morphology tuning. However, there exist few solid additives reported to meet such expectations. Herein, chlorine-functionalized graphdiyne (GCl) is successfully applied as a multifunctional solid additive to fine-tune the morphology and improve device efficiency as well as reproductivity for the first time. Compared with 15.6% efficiency for control devices, a record high efficiency of 17.3% with the certified one of 17.1% is obtained along with the simultaneous increase of short-circuit current (Jsc ) and fill factor (FF), displaying the state-of-the-art binary organic solar cells at present. The redshift of the film absorption, enhanced crystallinity, prominent phase separation, improved mobility, and decreased charge recombination synergistically account for the increase of Jsc and FF after introducing GCl into the blend film. Moreover, the addition of GCl dramatically reduces batch-to-batch variations benefiting mass production owing to the nonvolatile property of GCl. All these results confirm the efficacy of GCl to enhance device performance, demonstrating a promising application of GCl as a multifunctional solid additive in the field of OSCs.

Realizing 19.05% Efficiency Polymer Solar Cells by Progressively Improving Charge Extraction and Suppressing Charge Recombination

Abstract: Improving charge extraction and suppressing charge recombination are critically important to minimize the loss of absorbed photons and improve the device performance of polymer solar cells (PSCs). In this work, highly efficient PSCs are demonstrated by progressively improving the charge extraction and suppressing the charge recombination through the combination of side‐chain engineering of new nonfullerene acceptors (NFAs), adopting ternary blends, and introducing volatilizable solid additives. The 2D side chains on BTP‐Th induce a certain steric hindrance for molecular packing and phase separation, which is mitigated by fluorination of side chains on BTP‐FTh. Moreover, by introducing two highly crystalline molecules as the second acceptor and volatilizable solid additive, respectively, into the BTP‐FTh‐based host blend, the molecular crystallinity is significantly improved and the blend morphology is finely optimized. As expected, enhanced charge extraction and suppressed charge recombination are progressively realized, contributing to the largely improved fill factor (FF) of the resultant devices. Accompanied by the enhanced open‐circuit voltage (Voc) and short‐circuit current density (Jsc), a record high power conversion efficiency (PCE) of 19.05% is realized finally.

A Fully Non-fused Ring Acceptor with Planar Backbone and Near-IR Absorption for High Performance Polymer Solar Cells.

Abstract: Fused-ring electron acceptors have made significant progress in recent years, while the development of fully non-fused ring acceptors has been unsatisfactory. Here, two fully non-fused ring acceptors, o-4TBC-2F and m-4TBC-2F, were designed and synthesized. By regulating the location of the hexyloxy chains, o-4TBC-2F formed planar backbones, while m-4TBC-2F displayed a twisted backbone. Additionally, the o-4TBC-2F film showed a markedly red-shifted absorption after thermal annealing, which indicated the formation of J-aggregates. For fabrication of organic solar cells (OSCs), PBDB-T was used as a donor and blended with the two acceptors. The o-4TBC-2F-based blend films displayed higher charge mobilities, lower energy loss and a higher power conversion efficiency (PCE). The optimized devices based on o-4TBC-2F gave a PCE of 10.26 %, which was much higher than those based on m-4TBC-2F at 2.63 %, and it is one of the highest reported PCE values for fully non-fused ring electron acceptors.