Organic Semiconductor Transistor Achieves Highest Mobility and Efficiency To Date

Organic Semiconductor Transistor Achieves Highest Mobility, External Quantum Efficiency to Date

18 December 2013
Taiwanese researchers have created an organic semiconductor using a single organic nanoparticle that offers the highest-ever electron mobility value and external quantum efficiency registered to date. These accomplishments could benefit a broad range of applications, such as organic LED displays, organic solar cells and organic field-effect transistors.
Organic semiconducting devices have various advantages, like their low cost, high flexibility, small weight and easy processing, but one of the major limitations is their low electron mobility that hampers conductivity. The reason for this is electron scattering caused by structural defects in the form of grain boundaries. But researchers from the National Taiwan University and Academia Sinica managed to overcome this restriction by designing a transistor comprising only a single grain, according to a report on the experiment featured in the journal Applied Physics Letters.
The mobility of the organic semiconductor transistor designed by the team is 2-3 orders of magnitude greater than that of conventional counterparts made of polycrystalline films. The nanoparticle used is perylene tetracarboxylic dianhydride (PTCDA) and the mobility values of the device are 0.08 cm2/Vs at room temperature and 0.5 cm2/Vs at 80 K, or close to the mobility values of the PTCDA itself.
The organic semiconductor transistor also delivered the greatest external quantum efficiency observed so far, with the researchers putting the success down to the use of a single nanoparticle in the device, whose large surface area and small size ensured a short travelling distance for electrons.
The enhanced properties of organic semiconductor transistors could set the stage for the development of a wide range of devices and flexible displays such as Active Matrix Organic Light Emitting Diodes (AMOLEDs) in commercial smartphones, digital cameras and TVs and a paper-like display or an electronic paper, the researchers said.