posted on 2019-08-23, 17:36authored byZhi Wang, Xinming Zhuang, Yao Chen, Binghao Wang, Junsheng Yu, Wei Huang, Tobin J. Marks, Antonio Facchetti
Photolithographic-defined
films play an important role in modern
optoelectronics and are crucial for the development of advanced organic
thin-film transistors (OTFTs). Here, we explore a facile photoresist-free
photopatterning technique with natural carbohydrates and its use as
an OTFT gate dielectric. The effects of the cross-linkable chemical
structure on the cross-linking chemistry and dielectric strength of
the corresponding films are investigated in cinnamate-functionalized
carbohydrates from monomeric (glucose) to dimeric (sucrose) to polymeric
(cellulose) backbones. UV illumination of the cinnamate esters of
these carbohydrates leads to [2 + 2] cycloaddition and thus the formation
of robust cross-linked dielectric films in the irradiated areas. Using
propylene glycol monomethyl ether acetate as the solvent/developer,
patterned dielectric films with micrometer-sized features can be readily
fabricated. P- and N-type OTFTs are successfully demonstrated using
unpatterned/patterned cross-linked films as the gate dielectric and
pentacene and N,N′-1H,1H-perfluorobutyl dicyanoperylenecarboxydiimide
(PDIF-CN2) as the p- and n-channel semiconducting layers,
respectively. These results demonstrate that natural-derived polymer
gate dielectrics, which are soluble and patternable using biomass-derived
solvents, are promising for the realization of a more sustainable
OTFT technology.