Graphene as transparent conducting layer for high temperature thin film device applications

• Graphene membranes do not degrade after annealing at 1100 °C.
• They have been used as transparent conducting layer in thin film solar cells.
• This opens the way to the use of high temperature processing in thin film devices.
• For the same application, no alternative exists at present.

The use of graphene as transparent conducting layer in devices that require high temperature processing is proposed. The material shows stability upon thermal treatments up to 1100 °C if capped with a sacrificial silicon layer. The use of Cu foil or evaporated Cu as catalysts in Catalytic-Chemical Vapor Deposition growth gives rise to graphene of similar properties, which represents a promising result in view of its direct integration in microelectronic devices. Photovoltaic p–i–n thin film devices were fabricated on the as-deposited or annealed graphene membranes and compared with similar devices that incorporate as-deposited Indium Tin Oxide. No degradation in series resistance is observed for the annealed device. A 3.7% and 2.8% photovoltaic conversion efficiency is observed on the devices fabricated on as-transferred and on annealed graphene respectively. The major limitation derives from the high sheet resistance of the as-transferred state-of-the-art material. The results opens the way to the use of graphene in applications that require transparent conducting layers resistant to high temperature processing.

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