For the purpose of preparing well-organized functional surfaces, carbon and gold substrates were modified using electroreduction of a tetrahedral-shape preorganized tetra-aryldiazonium salt, leading to the deposition of ultrathin organic films. Characterization of the modified surfaces has been performed using cyclic voltammetry, X-ray photoelectron spectroscopy, infrared absorption spectroscopy, ellipsometry, atomic force microscopy, and contact angle measurements. The specific design of the tetra-aryldiazonium salts leads to an intrinsic structuring of the resulting organic films, allowing molecular sieving and current rectification properties toward redox probes in solution.