Development Of Polymer Semiconductors Research Articles

Regioregular Pyridal[1,2,3]Triazole‐Based Polymer Semiconductors for High Mobility and Near‐Infrared Light Emission Applications

AbstractThe development of polymer semiconductors with strong luminescence and high mobility has always been challenging, and achieving both properties together is considered paradoxical according to molecular design principles. Studies on novel molecular species with unique optoelectrical characteristics are limited. Herein, a novel fully rigid coplanar thiophene‐pyridal[1,2,3]triazole‐thiophene (T‐PT‐T) class structure with considerable intramolecular noncovalent interactions is proposed. To balance luminescence and carrier transport properties, a series of non‐conventional regioregular conjugated polymers (PPTs) with suitable energy gaps (Egs ≈ 1.8 eV) are developed, which exhibit near‐infrared (NIR, 700–1000 nm) light emission and high mobility. One of the synthesized polymers, PPT‐2, exhibits an excellent photoluminescence quantum yield (PLQY) of 9% in the solid‐state and a high mobility reaching 0.35 cm2 V−1 s−1, indicating superior performance compared to other NIR light‐emitting polymer semiconductors. The authors believe that the class structure of fully rigid coplanar “T‐PT‐T” could be harnessed to develop high‐mobility NIR light‐emitting polymer semiconductors.

(Invited) Development of High Mobility Polymer Semiconductors for p-Channel, n-Channel, and Ambipolar Thin Film Transistors

Polymer semiconductors are enabling materials for a wide range of printed electronics. As channel semiconductors for organic thin film transistors (OTFTs), charge carrier mobility on par with that of amorphous silicon (~0.5 cm2V-1s-1) or higher is required for many applications. The development of polymer semiconductors with high mobility and good ambient stability has been a great challenge. To improve the charge carrier transport, a combination of donor and acceptor units in an alternating fashion in the polymer backbone has been recently found very effective since the intermolecular donor-acceptor attraction can shorten the interchain distance. By utilizing this strategy, we have developed a number of donor-acceptor polymers semiconductors with very high mobility. One particular class of such polymers are based on a diketopyrrolopyrrole (DPP) acceptor building block. By carefully choosing the electron donor blocks, we have successfully developed p-type polymers with high mobility up to 6.9 cm2V-1s-1 and amibipolar polymers with balanced electron and hole mobility of 6.30 cm2V-1s-1 and 2.78 cm2V-1s-1, respectively. By using a ultra-thin layer (~2-5 nm) of polyethylenimine (PEI) to lower the work function of the source and drain contacts, we were able to block the hole injection and successfully transform ambipolar and even p-type transistors unipolar n-type transistors. This general approach to converting the transistor polarity broadens the scope of available polymer semiconductors for constructing n-channel transistors. References Li, Y.; Singh, S. P.; Sonar, P. Adv. Mater. 2010, 22, 4862-4866.Li, Y.; Sonar, P.; Singh, S. P.; Soh, M. S.; van Meurs, M.; Tan, J. J. Am. Chem. Soc. 2011, 133, 2198-2204.Li, Y.; Sonar, P.; Murphy, L.; Hong, W. Energy Environ. Sci. 2013, 6,1684-1710.Sun, B.; Hong, W.; Aziz, H.; Abukhdeir, N. M.; Li, Y. J. Mater. Chem. C 2013, 1, 4423-4426.Chen, S.; Sun, B.; Hong, W.; Aziz, H.; Meng, Y.; Li, Y. J. Mat. Chem. C. 2014, 2, 2183-2190.Sun, B.; Hong, W.; Yan, Z.; Aziz, H.; Li, Y. Adv. Mater. 2014, 26, 2636–2642.Sun, B.; Hong, W.; Thibau, E.; Aziz, H.; Lu, Z.H.; Li, Y. Organic Electronics 2014, 15, pp. 3787-3794.