Background and Originality
Content
Stability against oxygen is of great importance in the practical
applications of organic semiconductor materials, considering the
functional groups with high photoelectric activity are particularly
sensitive to oxygen when excited by light and
electricity.[1-2] The adverse effects of unstable
organic semiconductors as shortened service lifetime, deteriorative
mechanical property and optoelectronic performance are ubiquitous in
various single-molecular and hybrid systems which must work under
ambient conditions, including integrated
photovoltaic,[3-4] fluorescence
imaging,[5-7] organic light emitting diode
(OLED),[8] and organic field-effect transistors
(OFET).[9] To inhibit the degradation, several
kinds of additives such as light screeners/absorbers, excited-state
quenchers, antioxidants, radical scavengers have been developed
according to different stabilization mechanisms. Whereas for organic
semiconductors, the purity requirements are very severe to avoid the low
efficiency owing to the defect role of additive molecules. Besides,
customization of the molecular structures was proved effective for the
enhancement of stability, like replacing the covalent bonds with low
bond dissociation energy,[10] adding electron
withdrawing groups to increase the oxidation potentials[11] and so on. However, in many cases the
molecular design of electronic structure is not enough to meet the
functional and stability requirements at the same time.