No abstract

A record breaking PCE of 12.1% is achieved by incorporating 25 wt% of DR3TSBDT into a PTB7-Th:PC71BM host matrix.

No abstract

To systematically address the intriguing question of how siloxane termini of the side chains relative to alkylterminal groups affect the various inherent properties of conjugated polymersincluding optical, electrical, and morphological characteristicswe have synthesized model polymers (PDPPTT-R TG and PDPPTT-Si TG , together with an accompanying reference PDPPTT-ref) containing an identical backbone yet possessing different terminal groups. In order to fairly compare the end functionalities by eliminating molecular weight (M n ) and polydispersity index (PDI) variations that may act as complicating factors, the polymers used in this study have been controlled to have similar M n and PDI by carefully optimizing the catalyst system and reaction conditions. Although the molecular packing and orientation behaviors of PDPPTT-R TG and PDPPTT-Si TG are very different from each other, both polymers exhibit very high mobility exceeding 4.5 cm 2 V −1 s −1 . More meaningfully, organic field-effect transistors (OFETs) based on PDPPTT-Si TG are highly stable over extended periods in humid environments. Our findings provide new insights into the molecular design strategy aimed at the simultaneous enhancement of charge-carrier mobility and ambient stability, which is of great importance for practical OFET applications.

Compared with conventional organic solar cells (OSCs) based on single donor–acceptor pairs, terpolymer‐ and ternary‐based OSCs featuring multiple donor–acceptor pairs are promising strategies for enhancing the performance while maintaining an easy and simple synthetic process. Using multiple donor–acceptor pairs in the active layer, the key photovoltaic parameters (i.e., short‐circuit current density, open‐circuit voltage, and fill factor) governing the OSC characteristics can be simultaneously or individually improved by positive changes in light‐harvesting ability, molecular energy levels, and blend morphology. Here, these three major contributions are discussed with the aim of offering in‐depth insights in combined terpolymers and ternary systems. Recent exemplary cases of OSCs with multiple donor–acceptor pairs are summarized and more advanced research and perspectives for further developments in this field are highlighted.

Considering the special functions of fused-ring aromatic building blocks and Si-atom in high-performance donor-acceptor-conjugated materials at the same time, herein the synthesis of a novel fused-ring tricyclic heterocycle, triisopropylsilyl-substituted benzo[1,2-b:4,5-c′]dithiophene-4,8-dione (iBDD-Si), an isomer of well-known benzo[1,2-c:4,5-c′]dithiophene-4,8-dione is presented. The iBDD-Si-based copolymer series (PM6, PM6-5Si, PM6-10Si, and PM6-15Si) is synthesized via Stille polymerization, revealing fine-tuned optical and electrochemical properties, and molecular packing with varying iBDD-Si contents in the backbone. Organic solar cells are fabricated by pairing the copolymer donors with nonfullerene acceptor N3 and characterized. High power conversion efficiency of more than 17% is achieved using the PM6-5Sibased solar cell, which is attributed to the balanced charge transport, enhanced charge generation/dissociation kinetics, and minimized total energy and recombination losses. It is demonstrated that iBDD-Si is a promising backbone toolbox for various high-performance conjugated materials.

To understand the effects rendered on the relevant basic physical properties and device function by controlling the regiochemistry of the cyclopenta[1,2-b:5,4-b']dithiophene-fluorobenzo[c][1,2,5]thiadiazole polymer (hereafter referred to as the CDT-FBT polymer), two polymers, the regiorandom polymer (RA) and regioregular version (RR), respectively, are synthesized and characterized. In addition, an efficient route for synthesizing a key monomer for RR using various synthesis scope and optimizing the reaction conditions is discussed. Although RA exhibits optical, electrochemical, and morphological properties similar to RR, it shows better field-effect transistor (FET) performance. Surprisingly, by employing a capillarity-mediated sandwich-casting process on a nanogrooved substrate, an unprecedented mobility of 17.8 cm V s is obtained for RA-based FETs; this mobility value is almost twofold greater than those of the corresponding RR-based FETs. For the first time, this study challenges previously reported results in that high carrier mobility is related to the high degree of polymer order induced by the backbone regioregularity.

The π-extended (E)-2-(2-(thiophen-2-yl)-vinyl)­thiophene (TVT)-based polymers are an interesting class of semiconducting polymers because of their excellent mobilities and unique film microstructures. Despite these properties, the effect of the side-chain regiochemistry of TVT skeletons on the intrinsic properties of these polymers remains unclear. To investigate this, in this study, hexyl-substituted TVT subunits with a “tail in (TI)” or “tail out (TO)” regiosymmetrical arrangement were first introduced into diketo­pyrrolopyrrole (DPP)-based copolymer main chains to afford “isomeric” polymers PI and PO, respectively. By combining optical spectroscopy, atomic force microscopy (AFM), and grazing incidence X-ray diffraction (GIXD) data, we quantitatively characterized the aggregation, crystallization, and backbone orientation of both polymer films, which were then correlated to the charge-carrier mobilities. The PI film exhibited a bimodal packing motif comprising a mixture of edge-on and face-on orientations, which was beneficial for three-dimensional (3D) charge transport and resulted in a hole mobility 2-fold larger than that in the PO film (μh = 1.69 cm2 V–1 s–1). This comparative study substantiates the important role of the regiochemistry of TVT in developing high-performance semiconducting polymers.