Large Transconductance of Electrochemical Transistors Based on Fluorinated Donor-Acceptor Conjugated Polymers.

Organic electrochemical transistors (OECTs) have enormous potential for use in biosignal amplifiers, analyte sensors, and neuromorphic electronics owing to their exceptionally large transconductance. However, it is challenging to simultaneously achieve high charge carrier mobility and volumetric capacitance, the two most important figures of merit in OECTs. Herein, a method of achieving high-performance OECT with donor-acceptor conjugated copolymers by introducing fluorine units is proposed. A series of cyclopentadithiophene-benzothiadiazole (CDT-BT) copolymers for use in high-performance OECTs with enhanced charge carrier mobility (from 0.65 to 1.73 cm2·V-1·s-1) and extended volumetric capacitance (from 44.8 to 57.6 F·cm-3) by fluorine substitution is achieved. The increase in the volumetric capacitance of the fluorinated polymers is attributed to either an increase in the volume at which ions can enter the film or a decrease in the effective distance between the ions and polymer backbones. The fluorine substitution increases the backbone planarity of the CDT-BT copolymers, enabling more efficient charge carrier transport. The fluorination strategy of this work suggests the more versatile use of conjugated polymers for high-performance OECTs.

High-Performance Solution-Processed 2D P-Type WSe2 Transistors and Circuits through Molecular Doping.

Semiconducting ink based on 2D single-crystal flakes with dangling-bond-free surfaces enables the implementation of high-performance devices on form-free substrates by cost-effective and scalable printing processes. However, the lack of solution-processed p-type 2D semiconducting inks with high mobility is an obstacle to the development of complementary integrated circuits. Here, a versatile strategy of doping with Br2 is reported to enhance the hole mobility by orders of magnitude for p-type transistors with 2D layered materials. Br2 -doped WSe2 transistors show a field-effect hole mobility of more than 27 cm2  V-1  s-1 , and a high on/off current ratio of ≈107 , and exhibits excellent operational stability during the on-off switching, cycling, and bias stressing testing. Moreover, complementary inverters composed of patterned p-type WSe2 and n-type MoS2 layered films are demonstrated with an ultra-high gain of 1280 under a driving voltage (VDD ) of 7 V. This work unveils the high potential of solution-processed 2D semiconductors with low-temperature processability for flexible devices and monolithic circuitry.

High-performance hysteresis-free perovskite transistors through anion engineering.

Despite the impressive development of metal halide perovskites in diverse optoelectronics, progress on high-performance transistors employing state-of-the-art perovskite channels has been limited due to ion migration and large organic spacer isolation. Herein, we report high-performance hysteresis-free p-channel perovskite thin-film transistors (TFTs) based on methylammonium tin iodide (MASnI3) and rationalise the effects of halide (I/Br/Cl) anion engineering on film quality improvement and tin/iodine vacancy suppression, realising high hole mobilities of 20 cm2 V-1 s-1, current on/off ratios exceeding 107, and threshold voltages of 0 V along with high operational stabilities and reproducibilities. We reveal ion migration has a negligible contribution to the hysteresis of Sn-based perovskite TFTs; instead, minority carrier trapping is the primary cause. Finally, we integrate the perovskite TFTs with commercialised n-channel indium gallium zinc oxide TFTs on a single chip to construct high-gain complementary inverters, facilitating the development of halide perovskite semiconductors for printable electronics and circuits.