Field-effect-tuned lateral organic diodes

Abstract

The operation of organic diodes in solar cells and light-emitting displays strongly depends on the properties of the interfaces between hole- and electron-carrying organic semiconductors. Such interfaces are difficult to characterize, as they are usually buried under the surface or exist as an irregular “bulk heterojunction.” Using a unique fluorinated barrier layer-based lithographic technique, we fabricated a lateral organic p-n junction, allowing the first observation of the potential at an organic p-n interface simultaneously with the charge transport measurements. We find that the diode characteristics of the device (current output and rectification ratio) are consistent with the changes in the surface potentials near the junction, and the current-voltage curves and junction potentials are strongly and self-consistently modulated by a third, gate electrode. The generality of our technique makes this an attractive method to investigate the physics of organic semiconductor junctions. The lithographic technique is applicable to a wide variety of soft material patterns. The observation of built-in potentials makes an important connection between organic junctions and textbook descriptions of inorganic devices. Finally, these kinds of potentials may prove to be controlling factors in charge separation efficiency in organic photovoltaics.

Controlling Molecular Doping in Organic Semiconductors

“…The ability to precisely define doped regions with nanoscale resolution using photolithography has driven the computing revolution defined by Moore's law. We would like to apply the same photolithography techniques to organic semiconductors, however, due to mutual solubility most photoresists are incompatible with OSCs . Fluorinated photoresists, which are coated and stripped using fluorinated solvents, have been developed for this purpose.…”

Optimum bias of CMOS organic field effect transistor inverter through threshold adjustment of both p- and n-type devices

“…Atactic polystyrene was locally charged through the patterned Cytop/S1813 layer, leaving patterns of charges in the film. Note that while in our previous work [10] Cytop was used to protect the integrity of an organic semiconductor layer, here it is used to protect a charged dielectric region against alteration while a different region is oppositely charged. Finally, Cytop/S1813 layers are mechanically peeled off, yielding lithographically patterned and contrasting charged dielectric areas on the wafer.…”

Negative polarity of phenyl-C61 butyric acid methyl ester adjacent to donor macromolecule domains

“…We formed side-by-side (lateral) donor-acceptor junctions on insulating substrates using a fluoropolymer-based photolithography process developed by our lab. [13][14][15] SKPM was used to map the electrostatic potential profile of the exposed donoracceptor interface.…”