An agar sandwich method for patterning transparent conducting oxides

Transparent electrodes are frequently used to drive opto-electronic devices, and the patterning of these electrodes is essential. The present work demonstrates a facile means of removing transparent conducting oxides (TCOs) from a glass substrate in selected areas. When agarose gel (agar), a material typically used in desserts, is sandwiched between two TCO-coated glass substrates and connected to a dry cell, the TCO is removed from the glass at the agar stamping area within 2 min. This method allows etching of TCOs using acid-free, inexpensive, and readily available starting materials. Analyses by optical microscopy, transmission spectroscopy, electrical resistance measurements, X-ray diffraction, and X-ray photoelectron spectroscopy demonstrate that this etching occurs as a result of reduction of the TCO in conjunction with the electrolysis of water at the interface between the TCO and agar surfaces. Using this technique, high-throughput patterning of TCOs with an edge resolution of several micrometres was achieved. Furthermore, the shape of the agar template can be readily changed simply by cutting the agar using scissors. Therefore, this method provides a useful means for both researchers and students to easily fabricate patterned substrates for use in electronics and related technologies.