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All‐polymer solar cells have experienced rapid development in recent years by the emergence of polymerized small molecular acceptors (PSMAs). However, the strong chain entanglements of polymer donors (PDs) and polymer acceptors (PAs) decrease the miscibility of the resulting polymer mixtures, making it challenging to optimize the blend morphology. Herein, we designed three PAs, namely PBTPICm‐BDD, PBTPICγ‐BDD and PBTPICF‐BDD, by smartly using a BDD unit as the polymerized unit to copolymerize with different Y‐typed non‐fullerene small molecular acceptors (NF‐SMAs), thus achieving a certain degree of distortion and giving the polymer system enough internal space to reduce the entanglements of the polymer chains. Such effects increase the chances of the PD being interspersed into the acceptor material, which improve the solubility between the PD and PA. The PBTPICγ‐BDD and PBTPICF‐BDD displayed better miscibility with PBQx‐TCl, leading to a well optimized morphology. As a result, high power conversion efficiencies (PCEs) of 17.50 % and 17.17 % were achieved for PBQx‐TCl : PBTPICγ‐BDD and PBQx‐TCl : PBTPICF‐BDD devices, respectively. With the addition of PYFT‐o as the third component into PBQx‐TCl : PBTPICγ‐BDD blend to further extend the absorption spectral coverage and finely tune microstructures of the blend morphology, a remarkable PCE of 18.64 % was realized finally. [ABSTRACT FROM AUTHOR]

A desired morphology is essential for achieving efficient polymer solar cells. Donors and acceptors with appropriate crystallization can lead to a suitable phase-separated morphology for effective photocurrent generation process. Inspired by the success of Y6 acceptors and the 2D side chain engineering on popular polymer donors and small molecule acceptors, the usage of unique 2D 3,4-ethylene dioxythiophene (EDOT) side chains on Y6 to regulate its crystallinity, compatibility, and thus the related blend morphology is explored. In this study, two molecules of BTP-EDOT-4F and BTP-EDOT-4Cl with such unique 2D EDOT side chains are designed and synthesized. Due to the advantage of EDOT side chain, when these molecules are blended with PM6, the decent power conversion efficiencies (PCEs) of 16.78% and 15.87% are obtained. Furthermore, BTP-EDOT-4F is selected as the third component and added into PM6:L8-BO binary system to form ternary blends. The optimized crystallinity, compatibility, and morphology of such ternary blend are discovered in the presence of BTP-EDOT-4F, which enables efficient exciton dissociation and charge transport as well as decreased recombination, resulting in higher short circuit current density Jsc) and fill factor. Finally, the outstanding PCE of 18.56% is achieved in ternary blends containing PM6, L8-BO, and BTP-EDOT-4F. [ABSTRACT FROM AUTHOR]

Side‐chain engineering with heteroatoms is not only effective in tuning frontier molecular orbitals, but also possible for forming secondary bonds which can be utilized to planarize the molecular backbone, hence, improving the photon absorption as well as charge‐transport abilities of polymer solar‐cell (PSC) materials. Herein, two types of unconventional side chains, namely carboxylate and carbamate, containing various heteroatoms are introduced to the thiophene bridges in high performance benzodithiophene (BDT) based donor polymers to from the novel polymers PTzTz‐C and PTzTz‐N, respectively. In these polymers, non‐covalent O⋅⋅⋅S and N⋅⋅⋅H interactions induce a high tendency to aggregation. In a ternary‐blend PSC with PTzTz‐N added to the high‐performance D18 : BTP‐eC9 blend, complimentary absorption and improved thin‐film morphology were observed with a top power conversion efficiency of 18.76 %, which is an improvement of almost 5 % over the D18 : BTP‐eC9 binary blends. [ABSTRACT FROM AUTHOR]

The most popular approach to fabricating organic solar cells (OSCs) is solution processing a mixture of donor (D) and acceptor (A) materials into an active layer with a bulk heterojunction (BHJ) nanostructure. Herein, it is demonstrated that the interdigitated heterojunction (IHJ) is a more suitable nanostructure of the active layer for high‐performance OSCs whereas it is a long standing challenge to realize well‐defined IHJ structures. In this study, a facile and versatile sequential solution processing method is developed to produce an IHJ nanostructure with power conversion efficiency reaching 18.74% (18.10% for BHJ the counterpart) by fabricating a donor film with nanopores created by a wax additive, sequentially casting the acceptor on top of infiltrating the nanopores. Compared to the BHJ, the IHJ structure with an interpillar distance within the exciton diffusion length can afford a large bulk D/A interface for efficient exciton dissociation with a minimized charge recombination while free electrons and holes can transport to the respective electrodes through more straightforward pathways, thus enhance performance. Furthermore, the D or A phase in the IHJ device contacts with only one electrode, which can prevent shunting between the anode and cathode and facilitate the industrial mass production of OSCs. [ABSTRACT FROM AUTHOR]

Organic solar cells (OSCs) have attracted wide research interests in the past decades. In recent years, our group mainly focused on the new photovoltaic materials design and device engineering technologies for highly efficient OSCs. This account mainly summarizes our recent studies on the structural design of wide bandgap (WBG) polymers and their morphology control as well as applications in OSCs. Additionally, we introduce our work on binary and ternary blend devices and tandem solar cells containing these materials. What is the most favorite and original chemistry developed in your research group? We focus on design and synthesis of high‐performance organic semiconductors for photovoltaic applications. Our interests are exploring the relationships between the conjugated molecular structures and their photovoltaic properties. How do you get into this specific field? Could you please share some experiences with our readers? When I was in Singapore and USA as a postdoctoral research fellow, I found that the energy crisis and environmental pollution were becoming more and more serious. I believed that organic solar cell (OSC) would be sprung up in the near future and I needed to do something about it. Therefore, I begun to follow with interest the OSCs in 2006 and got into this field in 2007. How do you supervise your students? I am in pursuit of development on self‐thinking abilities of my students. More specifically, encourage and guide the students to find the problems, analyze the problems and figure out some ways to resolve the problems. What is the most important personality for scientific research? Intelligence, diligence and perseverance. What is your favorite journal(s)? Those journals with high scientific nature and good timeliness. Also, the reported results shall be reliable and repeated easily. [ABSTRACT FROM AUTHOR]