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Solar hydrogen production with semiconductor photocatalyst particles typically requires co‐catalysts, but since co‐catalysts are often deposited in situ, the rate of their nucleation/growth and role in parasitic light absorption are not well controlled. Herein a halted photodeposition‐dialysis method is introduced that affords unprecedented control over platinum (Pt) co‐catalyst loading and morphology on bulk heterojunction organic semiconductor photocatalyst nanoparticles. Pt loading and surface distribution are controlled by tuning the initial Pt precursor concentration and photodeposition time followed by removal of unreacted Pt precursor via dialysis. Applying this method with typical Pt deposition conditions gives a max H2 evolution rate of 140 mmol h−1 g−1 (based on semiconductor mass) with only 15.2 wt.% Pt deposited and suggests an optimum loading of <20 wt.% Pt, above which parasitic light absorption decreases the H2 evolution rate. Moreover, a peak H2 evolution >30 mmol h−1 g−1 is achieved with a Pt loading of only 1.01 wt.% by tuning the deposition conditions to favor a more uniform Pt coverage with small clusters and single atoms over larger Pt NPs. This represents a performance more than eight times higher compared to typical Pt photodepositions (based on Pt) and gives critical insights into optimizing performance. [ABSTRACT FROM AUTHOR]

This study focuses on the impact of dopant location in the semicrystalline structure of regioregular poly(3‐hexylthiophene‐2,5‐diyl) on the long‐term stability of thermoelectric properties probed in rub‐aligned films. Phase‐selective doping is possible by suitable choice of dopants. Anion exchange doping results in TFSI dopants located in both crystalline and amorphous domains whereas magic blue dopants are located in the amorphous phase only. The combination of rub‐alignment, increasing concentration doping, and anion exchange doping is effective to produce doped P3HT films with enhanced thermoelectric properties and stability. Transmission electron microscopy, polarized optical absorption spectroscopy, and transport measurements help identify different regimes of doping: crystalline domains are doped first by exchange of F4TCNQ− with TFSI−, followed by a progressive doping of amorphous regions. The best thermoelectric performances of TFSI‐exchanged P3HT lead to power factors in the 160–170 µW m−1 K−2 range. Despite similar TE performances, MB‐doped and TFSI‐exchanged P3HT films behave very differently on aging. Numerically exact kinetic Monte Carlo simulations clarify the origin of this difference. The retention of charges in any phase is crucial for the stability in conductivity, but the conductivity at long aging times, σ∞ is quantitatively determined by the specific phase retaining the charges. [ABSTRACT FROM AUTHOR]

Orienting polymer semiconductors is desirable to optimize device characteristics, provide insight into microstructure, and magnify subtle phase behavior. Here, a combination of uniaxial strain and subsequent heating of the donor–acceptor (DA) polymer PBnDT‐FTAZ is discovered to lead to exceptional optical dichroic ratios of up to 38 (and close to 50 near the polymer's absorption edge). This alignment is achieved due to the existence of a previously undetected thermotropic liquid crystal (LC) mesophase. The LC transition, not discernable through calorimetry, is uncovered through a combination of in situ UV–vis spectroscopy, X‐ray scattering, and dynamic mechanical analysis (DMA). Comparing PBnDT‐FTAZ to the non‐fluorinated PBnDT‐HTAZ and the homo polymer PBnDT, all of which show similar thermal transitions, reveals that exceptional alignment is only found in PBnDT‐FTAZ. This is attributed to the PBnDT‐FTAZ film having two distinct liquid crystal populations, and the polymer templating to a highly aligned, high‐clearing temperature population when heated. The DMA thermal relaxation behavior observed here is also seen in other DA conjugated polymers suggesting that such thermotropic LC mesophases may be common in these materials. These findings demonstrate a polymer semiconductor with remarkable alignment and uncover phase behavior with broad implications for process‐structure‐property relationships in polymer semiconductors. [ABSTRACT FROM AUTHOR]

In this communication, we report a novel acceptor structural unit, TVDPP, that can be distinguished from classical materials based on TDPP structures. By designing a synthetic route via retrosynthetic analysis, we successfully prepared this monomer and further prepared polymer P2TVDPP with high yield using a Stille-coupling polymerization reaction. The polymer showed several expected properties, such as high molecular weight, thermal stability, full planarity, small π−π stacking distance, smooth interface, and so on. The absorption spectra and energy levels of the polymer were characterized via photochemical and electrochemical analysis. The organic field-effect transistor (OFET), which is based on P2TVDPP, exhibited excellent carrier mobility and an on/off current ratio of 0.41 cm2 V−1 s−1 and ~107, respectively, which is an important step in expanding the significance of DPP-based materials in the field of optoelectronic devices and organic electronics. [ABSTRACT FROM AUTHOR]

Mobility of charge carriers in organic thin-film transistors (OTFTs) is one of the most important parameters, which is affected by the disorders in the semiconducting films. In general, realization of higher carrier concentration facilitates improved charge transport against these disorders. Here, we demonstrate in amorphous indacenodithiophen-co-benzothiadia (IDT-BT) based dual-gate organic thin-film transistors (DG-OTFTs) that the mobility can be robustly increased from 0.8 to 1.37 cm2 V−1 s−1, when voltage biases of opposite signs (negative one accumulate holes, positive one deplete holes) are applied on the dual independent gate electrodes. In details, the positive bias can confine the spatial distribution of the accumulated carriers near the negatively biased gate, leading to a higher effective carrier concentration with higher mobility. In addition, the interface confinement effect of carriers was further verified by two-dimensional numerical simulation, and calculations based on the variable range hopping method were performed to accurately reproduce the experimentally observed charge transport behavior in DG-OTFTs.

Polymer semiconductors are promising materials for stretchable, wearable, and implantable devices due to their intrinsic flexibility, facile functionalization, and solution processability at low temperatures. However, the crystalline domain of the conjugated structure for high charge carrier mobility in semiconducting polymers exhibits lower stretchability than that of the semi‐crystalline or amorphous domains. Herein, a set of thermoplastic soft semiconductors is synthesized with different ratios of diketopyrrolopyrrole–carbazole–diketopyrrolopyrrole (DPP‐Cz‐DPP)‐based hard segments and thiophene‐based aliphatic soft segments, having the similar structure of thermoplastic elastomers. The polymers exhibit decreased glassy temperatures with the increased content of the soft segments. The polymers show high crystallinity after copolymerization with a large‐sized DPP‐Cz‐DPP core and non‐conjugated segments due to an aggregation property of the conjugated core, still possessing a semi‐crystalline domain after annealing. The polymer films exhibit stretchability under strains of up to 60%. Organic field‐effect transistors fabricated using stretchable polymers show a mobility range of 0.125–0.005 cm2 V−1 s−1 with different proportions of the soft segment. The stretchability is improved significantly and the mobilities are decreased less when the content of the soft segment is increased. Therefore, this study presents a design principle for the development of a high‐performance stretchable semiconducting polymer. [ABSTRACT FROM AUTHOR]

Abstract Polymer semiconductors are promising materials for stretchable, wearable, and implantable devices due to their intrinsic flexibility, facile functionalization, and solution processability at low temperatures. However, the crystalline domain of the conjugated structure for high charge carrier mobility in semiconducting polymers exhibits lower stretchability than that of the semi‐crystalline or amorphous domains. Herein, a set of thermoplastic soft semiconductors is synthesized with different ratios of diketopyrrolopyrrole–carbazole–diketopyrrolopyrrole (DPP‐Cz‐DPP)‐based hard segments and thiophene‐based aliphatic soft segments, having the similar structure of thermoplastic elastomers. The polymers exhibit decreased glassy temperatures with the increased content of the soft segments. The polymers show high crystallinity after copolymerization with a large‐sized DPP‐Cz‐DPP core and non‐conjugated segments due to an aggregation property of the conjugated core, still possessing a semi‐crystalline domain after annealing. The polymer films exhibit stretchability under strains of up to 60%. Organic field‐effect transistors fabricated using stretchable polymers show a mobility range of 0.125–0.005 cm2 V−1 s−1 with different proportions of the soft segment. The stretchability is improved significantly and the mobilities are decreased less when the content of the soft segment is increased. Therefore, this study presents a design principle for the development of a high‐performance stretchable semiconducting polymer.

The backbone of diketopyrrolopyrrole‐thiophene‐vinylene‐thiophene‐based polymer semiconductors (PSCs) is modified with pyridine (Py) or bipyridine ligands to complex Fe(II) metal centers, allowing the metal–ligand complexes to act as mechanophores and dynamically crosslink the polymer chains. Mono‐ and bi‐dentate ligands are observed to exhibit different degrees of bond strengths, which subsequently affect the mechanical properties of these Wolf‐type‐II metallopolymers. The counter ion also plays a crucial role, as it is observed that Py‐Fe mechanophores with non‐coordinating BPh4– counter ions (Py‐FeB) exhibit better thin film ductility with lower elastic modulus, as compared to the coordinating chloro ligands (Py‐FeC). Interestingly, besides mechanical robustness, the electrical charge carrier mobility can also be enhanced concurrently when incorporating Py‐FeB mechanophores in PSCs. This is a unique observation among stretchable PSCs, especially that most reports to date describe a decreased mobility when the stretchability is improved. Next, it is determined that improvements to both mobility and stretchability are correlated to the solid‐state molecular ordering and dynamics of coordination bonds under strain, as elucidated via techniques of grazing‐incidence X‐ray diffraction and X‐ray absorption spectroscopy techniques, respectively. This study provides a viable approach to enhance both the mechanical and the electronic performance of polymer‐based soft devices. [ABSTRACT FROM AUTHOR]

Low-voltage organic memory transistors (LOMTs) as data storage units are crucial for the advancements of future flexible electronics. However, charge storage mechanism remains a great challenge. In this work, we used poly(2,5-bis(3-tetradecylthiophen-2-yl)thieno(3,2-b)thiophene) (PBTTT-C14) as the active layer and incorporated poly(methyl methacrylate) (PMMA) with the PBTTT-C14 through a simple blending process to fabricate LOMTs with porous structure. The function of the porous structure was to improve the carrier traps, which can effectively capture the holes at the charge trapping regions during the programming process. A maximum threshold voltage shift of 1.01 V was achieved when the weight ratio of PBTTT-C14 and PMMA is 7:3, and the LOMTs were operated under the programming process of âˆ'4 V/1 s. Impedance-admittance analyses were used to investigate the interfacial trap density of charge trapping regions, which is a supporter of the programming capability of LOMTs. An ultrathin dioctyl perylene tetracarboxylic diimide film was deposited on the active layer with porous structure in LOMTs. This film can increase the carriers’ erasing capability. A wide memory window of 1.64 V was obtained in LOMTs when the devices are operated under the erasing process of bias pulse of 3 V/1 s with the assistance of 2.5 mW cmâˆ'2 light irradiation. This study facilitates the development of high-performance LOMT device in fresh-type memory. [ABSTRACT FROM AUTHOR]

An inorganic p‐type CuInS2 semiconductor was combined with the semiconducting polymer of PNDI3OT‐Se1 and PNDI3OT‐Se2 with different HOMO/LUMO levels for photoelectrochemical hydrogen production. Charge transfer behaviors at polymer/CuInS2 junctions were investigated by electrochemical impedance spectroscopy. The heterojunction of p‐CuInS2 and n‐type polymer (both PNDI3OT‐Se1 and Se2) successfully made p‐n junctions and showed improved charge transfer. However, we found that higher HOMO levels of polymer than valence band maximum (VBM) of CuInS2 spurred charge recombination at interfaces. As a result, CuInS2/PNDI3OT‐Se1/TiO2/Pt, which has suitable energy levels matched between PNDI3OT‐Se1 and CuInS2, shows photocurrent (−15.67 mA cm−2) improved concretely when compared to a CuInS2/TiO2/Pt photoelectrode (−7.11 mA cm−2) at 0.0 V vs. RHE applied potential. Additionally, the photoelectrochemical stability of CuInS2/PNDI3OT‐Se1/TiO2/Pt photoelectrode was also investigated. [ABSTRACT FROM AUTHOR]

Organic photovoltaics (OPV) with junction controlled structure are prepared by the evaporative spray deposition using ultra-diluted solution (ESDUS) method with different donor polymer(p) and acceptor fullerene(n) ratio solution. In order to demonstrate the ideal junction, we fabricate the polymer solar cells with single junction(p/n), pin-layered junction (pin) or bulk-heterojunction (BHJ) active layer. The photovoltaic performance is dramatically varied with its junction. And the pin junction has best performance under the sunlight due to its good carrier generation and transport. And also we investigated the temperature dependence of the active layer morphologies at each substrate temperature 60 − 160 °C during its spray-depositing. The domain of active layer became smaller with increasing substrate temperature. The pin-layered cell sprayed at 120 °C gives best photovoltaic performance. Thus, ESDUS enables us to control the junction and morphologies of active layer. [ABSTRACT FROM AUTHOR]

The energy band structure of PEDOT:PSS films is regulated via secondary doping, the tribovoltaic effect is notably enhanced, and thus outputs and robustness of the polymeric tribovoltaic generator is significantly boosted in contact-separation or sliding mode. [Display omitted] • A polymeric tribovoltaic generator achieves boosted outputs and robustness through energy band engineering strategy. • The transferred charge quantity per motion cycle reaches 150.48 mC m−2 and 225.73 mC m−2 in contact-separation and sliding mode, respectively. • The tribovoltaic device achieves exceptional durability over 100,000 contact-separation cycles. • Exceptional humidity resistance is demonstrated. The semiconductor-based tribovoltaic nanogenerator (TVNG) garners distinctive characteristics of direct current output at low internal impedance, rendering it great potentials for self-powered electronics. We present a polymeric TVNG for achieving enhanced electrical outputs and robustness through secondary doping strategy. By utilizing the dimethyl sulfoxide (DMSO) as a dopant, the transport properties of semiconducting poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) can be modulated. We then demonstrate that the tribovoltaic outputs can be significantly enhanced due to the improved conductivity of the PEDOT:PSS and the enlarged Schottky barrier at the dynamic metal–semiconductor interfaces. The quantity of the transferred charge per motion cycle can reach 150.48 mC m−2 in contact-separation mode and 225.73 mC m−2 in sliding mode. Meantime, the dopant improves the flexibility of the PEDOT:PSS and hence the mechanical robustness of TVNG, allowing stable outputs for ∼ 100,000 contact-separation operations cycles or ∼ 36,000 bending cycles. Furthermore, the device also demonstrates exceptional humidity resistance, but confirms a coupling of tribovoltaic effect and electrochemical effect in high-humidity conditions (relative humidity over 90%). Therefore, our findings provide insightful strategies for future optimization of practical tribovoltaic devices. [ABSTRACT FROM AUTHOR]

We analyze the operation of thin-film transistor (TFT) devices where the active semiconductor is patterned into nanostripes (NSs). It is shown that using relatively large separations between stripes can improve current drive capability by more than a factor of 13 for many of the important material families of disordered and solution-processable TFTs. When comparing NS TFTs to unpatterned TFTs under the same operating conditions, NS devices show enhancements in peak carrier density and conductivity along the edges of the stripe. In addition to increasing the drive current, these carrier density enhancements are large enough to potentially lower the contact resistance. Short-channel effects are also greatly reduced, allowing the possibility of scaling down channel lengths for improved operation at high frequencies. This architecture will work especially well for TFT materials in which the mobility increases with carrier density, a common feature in many organic, polymer, and amorphous metal oxide semiconductors. The results of our analysis on NS TFTs not only make TFTs considerably more attractive for existing optoelectronic applications but NS patterning may also provide TFTs an opportunity to expand into new higher frequency and higher performance applications. [ABSTRACT FROM AUTHOR]

Abstract A facile stacking technology must be developed for various types of polymer semiconductors through a continuous solution process for successful commercial applications of organic electronics. In this study, we report a strategic method of stacking different polymer semiconductors from the same processing solvent in a non-destructive manner using vapor-phase iodine. We utilize the concept of reversible doping mechanism of iodine; interstitial iodine ions in the polymer backbone significantly reduce the solubility of entire films and such an immobilized phase can be quickly recovered to the initial phase via a simple vacuum treatment. Thus, a polymer–polymer p-n planar heterojunction (PHJ) can be realized using the same solvent without compromising the inherent electrical/optical characteristics of the polymer semiconductor. Detailed photophysical and morphological analyses on the doping and dedoping of polymeric semiconductors with iodine are discussed. As a target application of such iodine-mediated non-destructive stacking technology, a thin-film near-infrared(NIR)-selective polymeric photodiode, which can fully reflect the genuine advantages of a well-defined PHJ, is demonstrated. We successfully demonstrate a visible-blind and narrow-band NIR-selective photodiode with a high peak detectivity of 1.50 × 1011 Jones. Graphical abstract Image 1 Highlights • We suggest a facile and non-destructive multilayer stacking strategy of polymer semiconductors based on iodine doping/dedoping methods. • As using iodine-mediated multilayer stacking method, we demonstrate a thin-film, visible-blind and NIR-selective polymeric photodiode. • Our visible-blind and NIR-selective photodiode show a high peak detectivity of 1.50 × 1011 Jones. [ABSTRACT FROM AUTHOR]

Achieving a high-resolution display on a plastic substrate requires a low-temperature process to ensure dimensional stability during fabrication process, including the deposition of gate dielectrics. Evaluation platform to confirm the uniform insulating properties of organic dielectric material prior to actual application to organic thin-film transistor arrays were proposed. This test method enabled verification of the suitability of the low-temperature curable dielectric and chemical resistance during the fabrication process. A cross-linked poly(hydroxy imide) that can be cured at a low temperature of 130°C exhibited stable insulating properties in a large area that sudden breakdown was not observed in an electric field up to 4 MV/cm. Thiophene-thiazole-based copolymer semiconductor was used as an active layer and inkjet-printed. In all the processes, the temperature of the substrate was kept below 130 °C, and 4.8-inch electrophoretic display panels on a polyethylene naphthalate substrate with a resolution of 98 dpi was demonstrated. [ABSTRACT FROM AUTHOR]

Featured Application: Featured Application: Flexible Organic Integrated Circuits. The demonstration of the complementary integrated circuit using printing processes is indispensable for realizing electronic devices using organic thin film transistors. Although complementary integrated circuits have advantages such as low power consumption and a wide output voltage range, complementary integrated circuits fabricated by the printing method have problems regarding driving voltage and performance. Studies on fabrication processes of electronic circuits for printing technology, including optimization and simplification, are also important research topics. In this study, the fabrication process of the printed complementary integrated circuit was simplified by applying a p-type donor-acceptor (D-A) polymer semiconductor, which is not strongly affected by the electrode work function. An inverter circuit and the ring oscillator circuit were demonstrated using this process. The fabricated ring oscillator array showed excellent performance, with low voltage operation and low performance variation. [ABSTRACT FROM AUTHOR]

The polymer semiconductor-supported FePO4 (FePO4/g-C3N4) nanocomposites were prepared using FePO4 and g-C3N4 as materials by ultrasound mixing method. The nanocomposite samples were characterized by XRD, UV-Vis DRS, and PL. FePO4/g-C3N4 showed higher photocatalytic activity to degrade Rhodamine B than FePO4 and g-C3N4 under visible light irradiation. The feature of FePO4/g-C3N4 was attributed to efficient separation of the electron-hole pairs. The results of recycling photocatalytic experiment demonstrated that polymer/inorganic salt composites possessed higher stability. [ABSTRACT FROM AUTHOR]

• The mobility in dual-gate OTFT is improved from 0.8 to 1.37 cm2V−1s−1, with an accumulation-depletion operation mode. • The depletion gate constrains the carriers' spatial distribution, leading to a higher mobility. • Carriers' spatial confinement effect is verified by temperature dependent transport investigations and numerical simulations. • Mobility calculated by hopping transport theory reproduces the experimental results well. Mobility of charge carriers in organic thin-film transistors (OTFTs) is one of the most important parameters, which is affected by the disorders in the semiconducting films. In general, realization of higher carrier concentration facilitates improved charge transport against these disorders. Here, we demonstrate in amorphous indacenodithiophen-co-benzothiadia (IDT-BT) based dual-gate organic thin-film transistors (DG-OTFTs) that the mobility can be robustly increased from 0.8 to 1.37 cm2 V−1 s−1, when voltage biases of opposite signs (negative one accumulate holes, positive one deplete holes) are applied on the dual independent gate electrodes. In details, the positive bias can confine the spatial distribution of the accumulated carriers near the negatively biased gate, leading to a higher effective carrier concentration with higher mobility. In addition, the interface confinement effect of carriers was further verified by two-dimensional numerical simulation, and calculations based on the variable range hopping method were performed to accurately reproduce the experimentally observed charge transport behavior in DG-OTFTs. [ABSTRACT FROM AUTHOR]

The demonstration of the complementary integrated circuit using printing processes is indispensable for realizing electronic devices using organic thin film transistors. Although complementary integrated circuits have advantages such as low power consumption and a wide output voltage range, complementary integrated circuits fabricated by the printing method have problems regarding driving voltage and performance. Studies on fabrication processes of electronic circuits for printing technology, including optimization and simplification, are also important research topics. In this study, the fabrication process of the printed complementary integrated circuit was simplified by applying a p-type donor-acceptor (D-A) polymer semiconductor, which is not strongly affected by the electrode work function. An inverter circuit and the ring oscillator circuit were demonstrated using this process. The fabricated ring oscillator array showed excellent performance, with low voltage operation and low performance variation.

The enhanced performance uniformity of thin-film transistors (TFTs) fabricated by inkjet printing of polymer-semiconductor-wrapped single-walled carbon nanotube (PSC/SWCNT) networks blended with an insulating polymer binder was investigated. The inkjet-printed PSC/SWCNT network TFTs exhibited varied device performance with a field-effect mobility of 6.15 ± 6.75 cm 2 /V·s; the inkjet-printed TFTs fabricated using the poly(methyl methacrylate) (PMMA)-blended PSC/SWCNT layer as a channel exhibited relatively uniform device performance, with a field-effect mobility of 7.57 ± 3.32 cm 2 /V·s. This notable difference in device performance uniformity is attributed to the blended PMMA, which prevented the PSC/SWCNTs from forming random aggregates and facilitated their uniform percolation when they were inkjet-printed. [ABSTRACT FROM AUTHOR]

We demonstrate the development of organic semiconductor and passive material formulations optimized for photolithographic integration using existing photo-resist materials and technology. These materials can be coated and patterned to produce organic thin-film transistors suitable for integration into mass production processes with charge carrier mobility of greater than 2 cm2/Vs. [ABSTRACT FROM AUTHOR]

In this study, to adjust the desired molecular energy levels and bandgap energies of polymers for photovoltaic applications, a regular terpolymer structure was designed. A new regular terpolymer, poly(DPP4T- alt -TBP), containing diketopyrrolopyrrole (DPP), BT, and BP units in the repeating group was successfully synthesized. The DPP-BT monomeric unit in polymer backbone enhanced chain packing and induced a high-lying highest occupied molecular orbital (HOMO) level and the DPP-BP segment induced a deeper HOMO level. The lowest unoccupied molecular orbital (LUMO) level of the terpolymer was also controlled in a similar manner. The HOMO level of the terpolymer was similar to that of poly(DPP- alt -BP), and the energies of the LUMOs were governed by the DPP-BT unit. The polymer chain arrangement of the terpolymer on the substrate was observed to be a mix of face-on and edge-on orientations, which is a different chain arrangement mode to those shown in both poly(DPP- alt -BP) and poly(DPP- alt -BT). A TFT fabricated with poly(DPP4T- alt -TBP) had a charge carrier mobility of 0.59 cm 2 V −1 s −1 and a moderately high current on/off ratio. Furthermore, a polymer solar cell containing the terpolymer and PC 71 BM had a power conversion efficiency of 4.54%, which is significantly higher than those of the PCEs of poly(DPP- alt -BP) and poly(DPP- alt -BT)-based solar cells with identical device configurations. [ABSTRACT FROM AUTHOR]