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This work presents a series of novel quinoidal organic semiconductors based on diselenophene‐dithioalkylthiophene (DSpDST) conjugated cores with various side‐chain lengths (‐thiohexyl, ‐thiodecyl, and ‐thiotetradecyl, designated DSpDSTQ‐6, DSpDSTQ‐10, and DSpDSTQ‐14, respectively). The purpose of this research is to develop solution‐processable organic semiconductors using dicyanomethylene end‐capped organic small molecules for organic field effect transistors (OFETs) application. The physical, electrochemical, and electrical properties of these new DSpDSTQs are systematically studied, along with their performance in OFETs and thin film morphologies. Additionally, the molecular structures of DSpDSTQ are determined through density functional theory (DFT) calculations and single‐crystal X‐ray diffraction analysis. The results reveal the presence of intramolecular S (alkyl)···Se (selenophene) interactions, which result in a planar SR‐containing DSpDSTQ core, thereby promoting extended π‐orbital interactions and efficient charge transport in the OFETs. Moreover, the influence of thioalkyl side chain length on surface morphologies and microstructures is investigated. Remarkably, the compound with the shortest thioalkyl chain, DSpDSTQ‐6, demonstrates ambipolar carrier transport with the highest electron and hole mobilities of 0.334 and 0.463 cm2 V−1 s−1, respectively. These findings highlight the excellence of ambipolar characteristics of solution‐processable OFETs based on DSpDSTQs even under ambient conditions. [ABSTRACT FROM AUTHOR]

A novel quinoidal thienoisoindigo (TII)‐containing small molecule family with dicyanomethylene end‐capping units and various alkyl chains is synthesized as n‐type organic small molecules for solution‐processable organic field effect transistors (OFETs). The molecular structure of the 2‐hexyldecyl substituted derivative, TIIQ‐b16, is determined via single‐crystal X‐ray diffraction and shows that the TIIQ core is planar and exhibits molecular layers stacked in a "face‐to‐face" arrangement with short core intermolecular distances of 3.28 Å. The very planar core structure, shortest intermolecular N···H distance (2.52 Å), existence of an intramolecular non‐bonded contact between sulfur and oxygen atom (S···O) of 2.80 Å, and a very low‐lying LUMO energy level of −4.16 eV suggest that TIIQ molecules should be electron transporting semiconductors. The physical, thermal, and electrochemical properties as well as OFET performance and thin film morphologies of these new TIIQs are systematically studied. Thus, air‐processed TIIQ‐b16 OFETs exhibit an electron mobility up to 2.54 cm2 V−1 s−1 with a current ON/OFF ratio of 105–106, which is the first demonstration of TII‐based small molecules exhibiting unipolar electron transport characteristics and enhanced ambient stability. These results indicate that construction of quinoidal molecule from TII moiety is a successful approach to enhance n‐type charge transport characteristics. [ABSTRACT FROM AUTHOR]

Organic thermoelectric materials have garnered considerable attention in recent years for their potential in harvesting low-grade waste heat. The exploration of efficient and sustainable energy conversion technologies has prompted a significant interest in conjugated polymers (CPs) due to their tunable chemical structures, cost-effectiveness, environmental friendliness, light-weight, mechanically flexible and stretchable, high Seebeck coefficients, and low thermal conductivities, making them promising for organic thermoelectric devices. The optimization of the power factor in organic thermoelectric devices necessitates the incorporation of doping agents, which facilitates the intentional introduction of charge carriers in order to manipulate the electrical conductivity of the CP. The present review explores the recent developments in p-type doped CP-based thermoelectric thin films, with a particular emphasis on the intricate relationship between modifications of the chemical structure and the resultant thermoelectric properties, including electrical conductivities and power factors. Furthermore, various doping strategies, including doping processing methods and dopant structure engineering, are thoroughly examined. The comprehensive analysis presented herein contributes to the collective understanding of doped CP-based thermoelectric thin films, and offers insights into potential avenues for future research and development in this dynamically evolving field. • Recent progress on doped conjugated polymer-based thin film thermoelectric devices. • Polythiophenes and donor-acceptor polymers are included. • The various p-type dopants and doping methods are discussed. • The present review focuses on the structural modifications of conjugated polymers. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fabricate F4TCNQ-doped P3HT- b -PBA films for stretchable thermoelectric device. • P3HT-b-PBA 3k with PDMS show good stretchability (83.1% relative PF at 50% strain). • Intrinsically stretchable rod-coil block polymers for thermoelectric device. Organic-based thermoelectric materials have become increasingly popular for their ability to convert waste heat into electricity, coupled with their low processing costs, mechanical flexibility, and non-toxicity, making them an attractive option for wearable electronics. However, there is a lack of direct integration of intrinsically stretchable semiconducting polymers in wearable thermoelectric devices. This study investigates the potential of using poly(3-hexylthiophene)- block -poly(butyl acrylate) (P3HT- b -PBA) copolymers doped with 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) to develop stretchable thermoelectric devices. Two PBA block lengths, with number molecular weights (M n) of 3,000 and 6,000, were compared to pristine P3HT homopolymer. We found that all films exhibited edge-on orientations before and after doping, as determined by GIWAXS analysis. The lamellar distance increases while the π − π stacking distance decreases upon doping, indicating that the dopants preferentially allocate in the side-chain domain. Accordingly, the optimized power factor (PF) of the doped P3HT- b -PBA 3k and P3HT- b -PBA 6k films are found to be 2.13 and 1.42 μW m−1 K−2, respectively; and the stretchable thermoelectric device comprising P3HT- b -PBA 3k and a poly(dimethylsiloxane) (PDMS) substrate demonstrate good stretchability with a high PF of 1.77 μW m−1 K−2 at 50% strain, and a high PF retention 86.3% relative PF after 200 stretch/release cycles. This outstanding performance highlights the feasibility of fabricating stretchable thermoelectric device by using intrinsically stretchable semiconducting polymer. The study presents a promising approach for creating stretchable thermoelectric devices using conjugated/insulating block copolymers combining the thermoelectric properties of P3HT and the intrinsic softness of PBA. [ABSTRACT FROM AUTHOR]

A series of dialkylated tetrathienoacene ( TTAR )-based solution-processable small molecular organic semiconductors have been synthesized and characterized for organic field effect transistor (OFET) applications. The central dialkylated TTAR moiety was end-capped with thiophenylvinylthiophene ( TVT ), bithiophene ( bT ), and thienothiophene ( TT ) to afford new π-conjugated p-type active materials, DTVT-TTAR ( 1 ), DbT-TTAR ( 2 ), and DTT-TTAR ( 3 ), respectively. The physical and electrochemical properties and theoretical calculations as well as OFETs performance and thin film morphologies and microstructures of these new soluble TTAR s are systematically studied. Using a solution-shearing method, DTVT-TTAR exhibits p-channel transport with the highest mobility of up to 0.18 cm 2 V −1 s −1 and current ON/OFF ratios of 10 4 -10 6 , which is one of the highest hole mobilities for the solution-processed TTAR -based small molecules. [ABSTRACT FROM AUTHOR]

A series of new acceptor-donor-acceptor type conjugated small molecules with alkylated tetrathienoacene as donor and diketopyrrolopyrrole as acceptor moieties has been synthesized and characterized for solution-processed organic thin film transistor and organic photovoltaic applications. To investigate the effect of elongated conjugation on this system, thiophene and bithiophene units were systematically incorporated between the central core and end capped unit. In addition, the effect of alkyl chain substitution on diketopyrrolopyrrole was also examined. The thermal, optical, and electrochemical properties of these new molecules were investigated. The highest hole mobility of organic thin film transistor devices utilizing the solution sheared thin films of these compounds as an active layer is 1.0 × 10 −1 cm 2 V −1 s −1 . Whereas organic photovoltaic cells based on these new molecules exhibited the power conversion efficiencies as high as 2.9% when blends with [6,6]-phenyl-C 71 -butyric acid methyl ester. These performances are strongly correlated with their thin film morphologies. [ABSTRACT FROM AUTHOR]

Organic-inorganic lead halide perovskite solar cells have received global attention, and their upscaling to perovskite solar modules under ambient conditions merits investigation. Herein, an upscaled mini-module consisting of five serially interconnected cells demonstrate a power conversion efficiency of 6.18% measured on an aperture area of 10.4 cm2. The perovskite photovoltaic mini-module with an inverted configuration is realized on a 5 × 5.5 cm2 ITO glass substrate using a technique combining ultrasonic spray-coating of both the NiO x hole transport layer (HTL) and perovskite photoabsorber layer with mechanical scribing for module patterning. The influence of the post-annealing duration (3, 5, 8, 10, and 15 min) of the spray-coated NiO x films under optimized fabrication conditions of the perovskite mini-module is investigated. The bulk properties of the NiO x thin films as functions of annealing time and their interfacial properties with methylammonium lead iodide (MAPbI 3) are comprehensively discussed. The use of spray-coating to assemble the NiO x HTL/perovskite photoactive layer of the mini-module demonstrate the significant potential of this technique to facilitate scalable production of perovskite-based photovoltaic modules. Image 1 • Ultrasonic spray-coated NiO x hole transport layer and perovskite films. • Mini-module with five serially interconnected cells (aperture area of 10.4 cm2). • The physical properties of the NiO x film as functions of annealing time. [ABSTRACT FROM AUTHOR]