Transparent functional oxide stretchable electronics: micro-tectonics enabled high strain electrodes

Fully transparent and flexible electronic substrates that incorporate functional materials are the precursors to realising next-generation devices with sensing, self-powering and portable functionalities. Here, we demonstrate a universal process for transferring planar, transparent functional oxide thin films on to elastomeric polydimethylsiloxane (PDMS) substrates. This process overcomes the challenge of incorporating high-temperature-processed crystalline oxide materials with low-temperature organic substrates. The functionality of the process is demonstrated using indium tin oxide (ITO) thin films to realise fully transparent and flexible resistors. The ITO thin films on PDMS are shown to withstand uniaxial strains of 15%, enabled by microstructure tectonics. Furthermore, zinc oxide was transferred to display the versatility of this transfer process. Such a ubiquitous process for the transfer of functional thin films to elastomeric substrates will pave the way for touch sensing and energy harvesting for displays and electronics with flexible and transparent characteristics. A universal process for transferring planar, transparent functional oxide thin films on to elastomeric polydimethylsiloxane (PDMS) substrates is demonstrated. This overcomes the challenge of incorporating high-temperature-processed crystalline oxide materials with low-temperature organic substrates. The process is demonstrated using indium tin oxide (ITO) thin films to realise fully transparent and flexible resistors and zinc oxide thin films. The ITO thin films on PDMS are shown to withstand uniaxial strains of 15%, enabled by microstructure tectonics. This ubiquitous process will pave the way for touch sensing and energy harvesting for displays and electronics with flexible and transparent characteristics. Sharath Sriram, Madhu Bhaskaran and colleagues have developed a process for the transfer of high-temperature functional oxides onto flexible substrates, and used it to construct stretchable electrodes that can bear high strains. Structures of indium tin oxide (ITO) — a widely used transparent metallic conductor —were fabricated on a silicon wafer coated with platinum, and casted onto an elastic polymer substrate, polydimethylsiloxane (PDMS). The platinum–ITO–PDMS film is then easily peeled off, as platinum poorly adheres to the silicon substrate; the platinum layer is subsequently removed. When the resulting ITO–PDMS film is stretched, the ITO layer cracks into small, movable plates that remain connected with each other and are therefore still electrically conducting. The high flexibility of the plates means that the ITO–PDMS structure can withstand strains of up to 15%. These conducting structures may find applications in transparent flexible electronics, for example in displays, energy harvesters, or solar cells.