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Herein, a large‐area nanofabrication process is proposed for flexible, ultrathin, and ultrasmooth gold films with extraordinary electro‐optical performance, making them competitive as transparent conductive electrodes (TCEs). The approach circumvents the thermodynamic constraints associated with the physical deposition of thin film electrodes, where 3D growth and metal dewetting delay stable percolation until the deposited film thickness exceeds 8–10 nm. It is demonstrated that a postgrowth ion irradiation procedure of compact gold films with Ar+ beam at very low energies, around 100 eV, predominantly induces ballistic smoothing and grain boundary restructuring. This process finally leads to the formation of ultrasmooth and ultrathin gold films that remain compact even at a thickness of 4 nm, with a sheet resistance in the range of 60 Ω sq−1 and an optical transparency around 80%. Remarkably, the films remain percolated even at thicknesses as low as 3 nm, with a transparency exceeding 90% and a sheet resistance of 190 Ω sq−1. These figures are comparable to those of commercial TCEs and enable simple, scalable, all‐metal transparent contacts on both rigid and flexible substrates, with significant potential for optoelectronic applications. [ABSTRACT FROM AUTHOR]

• Growth of pentacene thin films on a rough surface, here defined ripples. • Nucleation of a substrate induced phase but also of the bulk phase. • Transition from the metastable thin film phase to the thermodynamically stable phase. • Defined epitaxial relationship between the thin film phase and the Campbell phase. Pentacene is known to grow on isotropic silicon oxide surfaces in a substrate-induced phase with fiber textured crystallites. This growth study reports on the growth of pentacene crystallites on uniaxially oriented surfaces. Silica substrates have been treated by ion beam sputtering so that ripples with a lateral corrugation length of 38 nm and a surface roughness of 1.3 nm are formed. Pentacene thin films with a nominal thickness in the range from 20 nm up to 300 nm are deposited on top of the rippled surfaces. The films are characterized by atomic force microscopy and grazing incidence X-ray diffraction. Bi-axially oriented crystals are formed due to the grooves of the substrate surface opening up the possibility of a defined in-plane alignment of the crystals. In a first stage of thin film growth, the thin film phase (TFP) of pentacene is formed, while in the later stage the bulk crystal structure (C, Campbell phase) also appears. Due to the bi-axial alignment of the crystallites the transition from the thin film phase to the bulk crystal structure can be directly investigated. An epitaxial relationship with (1 2 0) TFP || (2 1 0) C and [−2 1 0] TFP ||[1 −2 0] C is observed which can be explained by an adaption of the herringbone layers of both crystal structures. This work reveals one possible microscopic mechanism for the transition from the metastable substrate-induced phase of pentacene to its equilibrium bulk structure. [ABSTRACT FROM AUTHOR]