Organic Semiconductors

Organic semiconductors are a class of green, carbon-based materials. Their semiconducting character relies on the alternation of single and double bonds (π conjugation). The facile tunability of their composition by chemical tailoring opens up limitless possibilities to tailor their optoelectronic properties. Such optoelectronic versatility has enabled the use of organic semiconductors in a wide range of optoelectronic devices, including thin-film transistors, solar cells, photodetectors, and light-emitting diodes. Additionally, organic semiconductors possess high mechanical flexibility, and a large number of them can be deposited at low temperatures (e.g., down to room temperature) and through facile methods (e.g., printing and coating). This has enabled the development of organic optoelectronics in unique form factors and on flexible/stretchable substrates, which is highly attractive for emerging application areas such as the Internet of Things, wearable devices, low-cost flexible photovoltaics, etc.

Prof. Pecunia has extensively worked on organic semiconductors, exploring their charge-transport and optoelectronic properties in relation to materials properties, as well as their applications in large-area electronics and optoelectronics. For instance, Prof. Pecunia provided insight into the role of minority carriers in the operation of small-molecule and polymer thin-film transistors, and demonstrated the impact of charge trapping at reduced electric fields in polymer thin-film transistors. Additionally, Prof. Pecunia has developed hybrid circuit integration platforms comprising polymer thin-film transistors, and has explored their application in high-speed digital electronics as well as in low-voltage, low-power analog electronics.

At the Pecunia Research Group, we seek to understand and condition the optoelectronic properties of emerging solution-processible organic semiconductors in thin-film form, with the ultimate aim of harnessing them into high-performance optoelectronic devices. A particular focus area concerns organic semiconductor thin films whose photoconversion properties are selective to a narrow wavelength range (within the visible, near-infrared, or ultraviolet region) of the electromagnetic spectrum. By studying and engineering their photoconversion properties in relation to their composition and structure, we seek to develop high-performance narrowband organic photodetectors, which have formidable potential for manifold application areas such as color detection, computer vision, lab-on-chip devices, spectroscopy, and optical communications.

a) Impact of longitudinal field on the trapping effects in a polymer semiconductor film probed via field-effect measurements (10.1002/adma.201606938).

b) Versatility of the spectral properties of organic semiconductors, which makes them particularly attractive for narrowband photodetection (10.1088/978-0-7503-2663-6).

Representative publications

V. Pecunia†*, Organic Narrowband Photodetectors: Materials, Devices and Applications, Institute of Physics (IOP) Publishing, Bristol, UK, 2019. ISBN: 9780750326629, DOI: 10.1088/978-0-7503-2663-6.

V. Pecunia†*, M. Fattori, S. Abdinia, E. Cantatore, H. Sirringhaus, Organic and Amorphous-Metal-Oxide Flexible Analogue Electronics, Cambridge University Press, Cambridge, UK, 2018. ISBN: 9781108458191, DOI: 10.1017/9781108559034

K. Xia*, Y. Li, Y. Wang, L. Portilla, V. Pecunia†*, Narrowband-Absorption-Type Organic Photodetectors for the Far-Red Range Based on Fullerene-Free Bulk Heterojunctions, Advanced Optical Materials, 8, 1902056, 2020. DOI: 10.1002/adom.201902056

V. Pecunia†*, M. Nikolka*, A. Sou, I. Nasrallah, A. Y. Amin, I. McCulloch, H. Sirringhaus†, Trap Healing for High-Performance Low-Voltage Polymer Transistors and Solution-Based Analog Amplifiers on Foil, Advanced Materials, 29, 1606938, 2017. DOI: 10.1002/adma.201606938

Y. Hu*, V. Pecunia*, L. Jiang, C. Di, X. Gao, H. Sirringhaus†, Scanning Kelvin Probe Microscopy Investigation of the Role of Minority Carriers on the Switching Characteristics of Organic Field-Effect Transistors, Advanced Materials, 28, 4713–4719, 2016. DOI: 10.1002/adma.201503812