Jiangsheng Yu

Bio: Jiangsheng Yu is an academic researcher from Nanjing University of Science and Technology. The author has contributed to research in topics: Organic solar cell & Polymer solar cell. The author has an hindex of 21, co-authored 54 publications receiving 1576 citations. Previous affiliations of Jiangsheng Yu include University of Washington.

Dithieno[3,2-b:2',3'-d]pyrrol Fused Nonfullerene Acceptors Enabling Over 13% Efficiency for Organic Solar Cells.

Abstract: A new electron-rich central building block, 5,5,12,12-tetrakis(4-hexylphenyl)-indacenobis-(dithieno[3,2-b:2',3'-d]pyrrol) (INP), and two derivative nonfullerene acceptors (INPIC and INPIC-4F) are designed and synthesized. The two molecules reveal broad (600-900 nm) and strong absorption due to the satisfactory electron-donating ability of INP. Compared with its counterpart INPIC, fluorinated nonfullerene acceptor INPIC-4F exhibits a stronger near-infrared absorption with a narrower optical bandgap of 1.39 eV, an improved crystallinity with higher electron mobility, and down-shifted highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels. Organic solar cells (OSCs) based on INPIC-4F exhibit a high power conversion efficiency (PCE) of 13.13% and a relatively low energy loss of 0.54 eV, which is among the highest efficiencies reported for binary OSCs in the literature. The results demonstrate the great potential of the new INP as an electron-donating building block for constructing high-performance nonfullerene acceptors for OSCs.

Ternary nonfullerene polymer solar cells with efficiency >13.7% by integrating the advantages of the materials and two binary cells

Abstract: Highly efficient ternary polymer solar cells (PSCs) are fabricated from two well-compatible small molecular nonfullerene acceptors (INPIC-4F and MeIC1) and one polymer donor, PBDB-T. The power conversion efficiency (PCE) of the INPIC-4F or MeIC1 based binary PSCs reaches 12.55% and 11.53%. Based on these efficient binary PSCs, a high PCE of 13.73% is achieved in the ternary PSCs with 50 wt% MeIC1 in the acceptors, resulting from the simultaneously improved short circuit current (JSC) of 21.86 mA cm−2, open circuit voltage (VOC) of 0.88 V and fill factor (FF) of 71.39%. The PCE improvement of the ternary PSCs should be mainly attributed to the simultaneously optimized photon harvesting and film morphology of the ternary active layers. This result may provide more in-depth insight into the material selection criteria for fabricating highly efficient ternary PSCs: (i) the complementary absorption spectra and good compatibility of the used materials; (ii) the complementary photovoltaic parameters of the corresponding two binary PSCs.

Molecular engineering of central fused-ring cores of non-fullerene acceptors for high-efficiency organic solar cells

Abstract: Organic solar cells (OSCs) using bulk-heterojunction (BHJ) blends of polymer donors and non-fullerene acceptors (NFAs) have witnessed significant progress in recent years. NFAs, especially, fused-ring electron acceptors (FREAs) adopting acceptor–donor–acceptor (A–D–A) structures have contributed most high-efficiency OSCs, pushing the power conversion efficiency (PCE) to over 15% and 17% for single-junction and tandem devices, respectively. The vibrant development of novel FREAs is largely attributed to their versatility in manipulating energy levels and molecular ordering via chemical modification. FREAs typically feature coplanar aromatic fused-rings as D cores and two electron-deficient A units as end caps. In this review, we try to summarize the recent advancement in molecular engineering of central fused-ring cores of FREAs for high-efficiency OSCs. The impact of such core engineering on the light absorption, energy levels, electron mobility, and photovoltaic performance of the resultant FREAs is discussed. Some guidelines for future molecular design are suggested from the aspects of improving light absorption, the fill factor, the driving force and voltage loss. Finally, we give an outlook on the remaining challenges and promising directions towards the commercialization of OSCs.

Nonfullerene Acceptor for Organic Solar Cells with Chlorination on Dithieno[3,2-b:2′,3′-d]pyrrol Fused-Ring

Abstract: A narrow-band-gap molecular acceptor, IPIC-4Cl, featuring an indacenobis(dithieno[3,2-b:2′,3′-d]pyrrol) (INP) core with 2-butyl-1-octyl side chains and chlorinated (dicyanomethylidene)-indan-1-one (IC) as electron-accepting end group, has been rationally designed as nonfullerene acceptors (NFAs) for organic solar cells (OSCs). The impact of chlorination on the acceptor unit is revealed by a comparison study with two counterpart NFAs bearing a fluorinated or nonhalogenated IC unit. The synergetic photophysical and morphological analyses reveal that PBDB-T:IPIC-4Cl blend possesses efficient exciton dissociation and charge collection integrated with higher crystallinity and optimized phase separation. Consequently, the OSCs constructed by PBDB-T:IPIC-4Cl obtain a champion power conversion efficiency (PCE) of 13.4% with an extremely low energy loss of 0.51 eV. More encouragingly, we achieve a higher photovoltaic performance of 14.3% for ternary solar cells by combining an optimal amount of PC71BM with PBDB-T:...

Non-fullerene acceptors for organic solar cells

Abstract: Non-fullerene acceptors (NFAs) are currently a major focus of research in the development of bulk-heterojunction organic solar cells (OSCs). In contrast to the widely used fullerene acceptors (FAs), the optical properties and electronic energy levels of NFAs can be readily tuned. NFA-based OSCs can also achieve greater thermal stability and photochemical stability, as well as longer device lifetimes, than their FA-based counterparts. Historically, the performance of NFA OSCs has lagged behind that of fullerene devices. However, recent developments have led to a rapid increase in power conversion efficiencies for NFA OSCs, with values now exceeding 13%, demonstrating the viability of using NFAs to replace FAs in next-generation high-performance OSCs. This Review discusses the important work that has led to this remarkable progress, focusing on the two most promising NFA classes to date: rylene diimide-based materials and materials based on fused aromatic cores with strong electron-accepting end groups. The key structure–property relationships, donor–acceptor matching criteria and aspects of device physics are discussed. Finally, we consider the remaining challenges and promising future directions for the NFA OSCs field. Non-fullerene acceptors have been widely used in organic solar cells over the past 3 years. This Review focuses on the two most promising classes of non-fullerene acceptors — rylene diimide-based materials and fused-ring electron acceptors — and discusses structure–property relationships, donor– acceptor matching criteria and device physics, as well as future research directions for the field.

Nonfullerene Acceptor Molecules for Bulk Heterojunction Organic Solar Cells

Abstract: The bulk-heterojunction blend of an electron donor and an electron acceptor material is the key component in a solution-processed organic photovoltaic device. In the past decades, a p-type conjugated polymer and an n-type fullerene derivative have been the most commonly used electron donor and electron acceptor, respectively. While most advances of the device performance come from the design of new polymer donors, fullerene derivatives have almost been exclusively used as electron acceptors in organic photovoltaics. Recently, nonfullerene acceptor materials, particularly small molecules and oligomers, have emerged as a promising alternative to replace fullerene derivatives. Compared to fullerenes, these new acceptors are generally synthesized from diversified, low-cost routes based on building block materials with extraordinary chemical, thermal, and photostability. The facile functionalization of these molecules affords excellent tunability to their optoelectronic and electrochemical properties. Within t...

Non-fullerene acceptors with branched side chains and improved molecular packing to exceed 18% efficiency in organic solar cells

Abstract: Molecular design of non-fullerene acceptors is of vital importance for high-efficiency organic solar cells. The branched alkyl chain modification is often regarded as a counter-intuitive approach, as it may introduce an undesirable steric hindrance that reduces charge transport in non-fullerene acceptors. Here we show the design and synthesis of a highly efficient non-fullerene acceptor family by substituting the beta position of the thiophene unit on a Y6-based dithienothiophen[3,2-b]-pyrrolobenzothiadiazole core with branched alkyl chains. It was found that such a modification to a different alkyl chain length could completely change the molecular packing behaviour of non-fullerene acceptors, leading to improved structural order and charge transport in thin films. An unprecedented efficiency of 18.32% (certified value of 17.9%) with a fill factor of 81.5% is achieved for single-junction organic solar cells. This work reveals the importance of the branched alkyl chain topology in tuning the molecular packing and blend morphology, which leads to improved organic photovoltaic performance. Molecular design of acceptor and donor molecules has enabled major progress in organic photovoltaics. Li et al. show that branched alkyl chains in non-fullerene acceptors allow favourable morphology in the active layer, enabling a certified device efficiency of 17.9%.

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...