Flexible Transparent Electrodes Formed from Template‐Patterned Thin‐Film Silver

Abstract

AbstractTemplate‐patterned, flexible transparent electrodes (TEs) formed from an ultrathin silver film on top of a commercial optical adhesive – Norland Optical Adhesive 63 (NOA63) – are reported. NOA63 is shown to be an effective base‐layer for ultrathin silver films that advantageously prevents coalescence of vapor‐deposited silver atoms into large, isolated islands (Volmer‐Weber growth), and so aids the formation of ultrasmooth continuous films. 12 nm silver films on top of free‐standing NOA63 combine high, haze‐free visible‐light transparency (T ≈ 60% at 550 nm) with low sheet‐resistance ( ≈ 16 Ω sq−1), and exhibit excellent resilience to bending, making them attractive candidates for flexible TEs. Etching the NOA63 base‐layer with an oxygen plasma before silver deposition causes the silver to laterally segregate into isolated pillars, resulting in a much higher sheet resistance ( > 8 × 106 Ω sq-1) than silver grown on pristine NOA63 . Hence, by selectively etching NOA63 before metal deposition, insulating regions may be defined within an otherwise conducting silver film, resulting in a differentially conductive film that can serve as a patterned TE for flexible devices. Transmittance may be increased (to 79% at 550 nm) by depositing an antireflective layer of Al2O3 on the Ag layer at the cost of reduced flexibility.