Phototransistors and Photoswitches From an Ultraclosely $\pi$-Stacked Organic Semiconductor

Abstract

In this letter, high-performance organic phototransistors and photoswitches based on an ultraclosely <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\pi$</tex></formula> -stacked organic semiconductor, i.e., titanyl phthalocyanine, are fabricated. The p-type transistor exhibited high performance with a hole mobility of <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\sim\!\hbox{4. 5}\ \hbox{cm}^{2}\cdot\hbox{V}^{-1}\cdot \hbox{s}^{-1}$</tex> </formula> and an on/off ratio higher than <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\hbox{3.1} \times \hbox{10}^{7}$</tex> </formula> . Phototransistors exhibited high-photoresponse properties with a responsivity at 10.5 A/W and a photosensitivity up to <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\hbox{2.7} \times \hbox{10}^{5}$</tex></formula> . The high performance of the devices showed their potential application in optoelectronic organic integrated circuits.