Weichao Chen

Bio: Weichao Chen is an academic researcher from Qingdao University. The author has contributed to research in topics: Polymer solar cell & Organic solar cell. The author has an hindex of 25, co-authored 74 publications receiving 1834 citations. Previous affiliations of Weichao Chen include Donghua University & Chinese Academy of Sciences.

Enhanced Photovoltaic Performance of Indacenodithiophene-Quinoxaline Copolymers by Side- Chain Modulation

Abstract: Two pairs of indacenodithiophene (IDT) and quinoxaline-based copolymers with meta- or para-hexyl-phenyl side chains on the IDT unit are synthesized. The meta-substituted polymers offer better solubility, higher molecular weight for both fluorinated and non-fluorinated copolymers, and a superior photovoltaic performance with a power conversion efficiency of 7.8%. The side-chain design strategy presented is an efficient way to produce high performance conjugated polymers for organic electronics.

High-Performance Photovoltaic Polymers Employing Symmetry-Breaking Building Blocks

Abstract: Two 1D-2D asymmetric benzodithiophenes (BDTs) as donor building blocks are designed and synthesized, combining the advantages of both 1D and 2D symmetric BDTs. The photovoltaic properties of the asymmetric BDT-based polymers are improved greatly in comparison with corresponding symmetric BDT-based polymers. This work provides a new approach to design prospective organic optoelectronic materials employing the symmetry-breaking strategy.

Extending π-Conjugation System with Benzene: An Effective Method To Improve the Properties of Benzodithiophene-Based Polymer for Highly Efficient Organic Solar Cells

Abstract: To obtain a polymer based on benzodithiophene (BDT) owning both a largely extended π-conjugation system and a low-lying highest occupied molecular orbital (HOMO), a polymer (PBDTBzT-DTffBT) containing benzothienyl-substituted BDT is designed and synthesized. Compared with the polymer (PBDTT-DTffBT) based on thienyl-substituted BDT, PBDTBzT-DTffBT exhibits better thermal stabilities, red-shifted absorption spectra, and stronger intermolecular interactions. The HOMO and lowest unoccupied molecular orbital (LUMO) in PBDTBzT-DTffBT are decreased by 0.11 and 0.13 eV, respectively, which should be attributed to the contribution of the electron-withdrawing group benzene. Polymer solar cells (PSCs) based on PBDTBzT-DTffBT and [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) exhibit a maximum power conversion efficiency (PCE) of 7.30% with a large open-circuit voltage of 0.90 V under AM 1.5G illumination (100 mW/cm2). The PCE is 36% higher than that of the PSCs derived from PBDTT-DTffBT. These findings provide ...

Revealing the Position Effect of an Alkylthio Side Chain in Phenyl-Substituted Benzodithiophene-Based Donor Polymers on the Photovoltaic Performance of Non-Fullerene Organic Solar Cells

Abstract: In this work, position effects of an alkylthio side chain were investigated by designing and synthesizing two copolymers based on a phenyl-substituted benzo[1,2-b:4,5-b′]dithiophene (BDTP) and difluorobenzotriazole (FTAZ). The polymer based on the meta-position-alkylthiolated BDTP, named m-PBDTPS-FTAZ, showed a relatively broader bandgap (2.00 vs 1.96 eV) and lower highest occupied molecular orbital (HOMO) energy level (-5.40 vs-5.32 eV) than its para-positioned structural isomeric analogue polymer (named p-PBDTPS-FTAZ), that is, m- A nd p-PBDTPS-FTAZ with the side chain structured as ethylhexyl-in the phenyl unit and hexyldecyl-in the FTAZ moiety. When blended with ITIC, m-PBDTPS-FTAZ showed a comparable crystallinity but more uniform morphology compared to that of p-PBDTPS-FTAZ. A high power conversion efficiency of 13.16% was achieved for m-PBDTPS-FTAZ:ITIC devices with a high open circuit voltage (VOC) of 0.95 V, which is higher than that of p-PBDTPS-FTAZ:ITIC devices (10.86%) with a VOC of 0.89 V. Therefore, m-BDTPS could be an effective donor unit to construct high-efficiency polymers due to its effectively decreased HOMO energy level of polymers while still maintaining good molecular stacking.

Molecular Design of Benzodithiophene-Based Organic Photovoltaic Materials.

Abstract: Advances in the design and application of highly efficient conjugated polymers and small molecules over the past years have enabled the rapid progress in the development of organic photovoltaic (OPV) technology as a promising alternative to conventional solar cells. Among the numerous OPV materials, benzodithiophene (BDT)-based polymers and small molecules have come to the fore in achieving outstanding power conversion efficiency (PCE) and breaking 10% efficiency barrier in the single junction OPV devices. Remarkably, the OPV device featured by BDT-based polymer has recently demonstrated an impressive PCE of 11.21%, indicating the great potential of this class of materials in commercial photovoltaic applications. In this review, we offered an overview of the organic photovoltaic materials based on BDT from the aspects of backbones, functional groups, alkyl chains, and device performance, trying to provide a guideline about the structure-performance relationship. We believe more exciting BDT-based photovol...

Imide- and Amide-Functionalized Polymer Semiconductors

Abstract: Xugang Guo,*,† Antonio Facchetti,*,‡,§ and Tobin J. Marks*,‡ †Department of Materials Science and Engineering, South University of Science and Technology of China, No. 1088, Xueyuan Road, Shenzhen, Guangdong 518055, China ‡Department of Chemistry and the Materials Research Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States Polyera Corporation, 8045 Lamon Avenue, Skokie, Illinois 60077, United States

Side-Chain Isomerization on an n-type Organic Semiconductor ITIC Acceptor Makes 11.77% High Efficiency Polymer Solar Cells

Abstract: Low bandgap n-type organic semiconductor (n-OS) ITIC has attracted great attention for the application as an acceptor with medium bandgap p-type conjugated polymer as donor in nonfullerene polymer solar cells (PSCs) because of its attractive photovoltaic performance. Here we report a modification on the molecular structure of ITIC by side-chain isomerization with meta-alkyl-phenyl substitution, m-ITIC, to further improve its photovoltaic performance. In a comparison with its isomeric counterpart ITIC with para-alkyl-phenyl substitution, m-ITIC shows a higher film absorption coefficient, a larger crystalline coherence, and higher electron mobility. These inherent advantages of m-ITIC resulted in a higher power conversion efficiency (PCE) of 11.77% for the nonfullerene PSCs with m-ITIC as acceptor and a medium bandgap polymer J61 as donor, which is significantly improved over that (10.57%) of the corresponding devices with ITIC as acceptor. To the best of our knowledge, the PCE of 11.77% is one of the highe...