Boyu Peng

A Low‐Operating‐Power and Flexible Active‐Matrix Organic‐Transistor Temperature‐Sensor Array

An organic flexible temperature-sensor array exhibits great potential in health monitoring and other biomedical applications. The actively addressed 16 × 16 temperature sensor array reaches 100% yield rate and provides 2D temperature information of the objects placed in contact, even if the object has an irregular shape. The current device allows defect predictions of electronic devices, remote sensing of harsh environments, and e-skin applications.

High performance organic transistor active-matrix driver developed on paper substrate

The fabrication of electronic circuits on unconventional substrates largely broadens their application areas. For example, green electronics achieved through utilization of biodegradable or recyclable substrates, can mitigate the solid waste problems that arise at the end of their lifespan. Here, we combine screen-printing, high precision laser drilling and thermal evaporation, to fabricate organic field effect transistor (OFET) active-matrix (AM) arrays onto standard printer paper. The devices show a mobility and on/off ratio as high as 0.56 cm2V−1s−1 and 109 respectively. Small electrode overlap gives rise to a cut-off frequency of 39 kHz, which supports that our AM array is suitable for novel practical applications. We demonstrate an 8 × 8 AM light emitting diode (LED) driver with programmable scanning and information display functions. The AM array structure has excellent potential for scaling up.

A simulation-assisted solution-processing method for a large-area, high-performance C10-DNTT organic semiconductor crystal

A quasi-equilibrium low-speed solution shearing method to deposit C10-DNTT is developed. We focus on quantifying the effects of the key parameters, including the temperature, surface energy and receding speed of the contact line to understand the crystallization mechanisms. A finite element model that takes into consideration fluid dynamics, heat transfer and mass diffusion has been developed to simulate the experimental process. The optimized parameters obtained from the model simulation provide large-area (>1 cm2) and well-oriented crystals with high uniformity. The single crystallinity is confirmed by SAED and the fabricated devices show a high charge carrier mobility of up to 12.5 cm2 V−1 s−1 (average of 9.0 cm2 V−1 s−1) and a high on/off ratio of 2 × 109. A useful guideline on how to optimally select the experimental parameters for meniscus-guided deposition methods is provided, based on which high-quality crystals are successfully grown on a solution-processed high-k gate dielectric, which achieves mobility of up to 4.2 cm2 V−1 s−1 (an average of 3.0 cm2 V−1 s−1) in an operating range of 4 V.

Fully transparent organic transistors with junction-free metallic network electrodes

We utilize highly transparent, junction-free metal network electrodes to fabricate fully transparent organic field effect transistors (OFETs). The patterned transparent Ag networks are developed by polymer crack template with adjustable line width and density. Sheet resistance of the network is 6.8 Ω/sq and optical transparency in the whole visible range is higher than 80%. The bottom contact OFETs with DNTT active layer and parylene-C dielectric insulator show a maximum field-effect mobility of 0.13 cm2/V s (average mobility is 0.12 cm2/V s) and on/off ratio is higher than 107. The current OFETs show great potential for applications in the next generation of transparent and flexible electronics.

Flexible transistor active matrix array with all screen-printed electrodes

Flexible transistor active matrix array is fabricated on PEN substrate using all screen-printed gate, source and drain electrodes. Parylene-C and DNTT act as gate dielectric layer and semiconductor, respectively. The transistor possesses high mobility (0.33 cm2V-1 s-1), large on/off ratio (< 106) and low leakage current (~10 pA). Active matrix array consists of 10×10 transistors were demonstrated. Transistors exhibited average mobility of 0.29 cm2V-1s-1 and on/off ratio larger than 104 in array form. In the transistor array, we achieve 75μm channel length and a size of 2 mm × 2 mm for each element in the array which indicates the current screen-printing method has large potential in large-area circuits and display applications.