Monolayer colloidal lithography protocol: theoretical assessment and applicative potentialities for metal nanohole fabrication

Abstract

Polystyrene colloids adsorbed onto a poly(diallyldimethylammonium chloride) (PDDA) monolayer is the model-system exploited to present and discuss both theoretical assessment and extended practical roadmap of the monolayer colloidal lithography (MNL-CL) protocol, recently developed by the authors to efficiently simplify and speed-up the deposition of template colloidal masks. Advantages of the MNL-CL protocol are demonstrated, in terms of ordering and coverage optimization of colloid arrangements, over the entire coverage range of its application, that is even under the commonly disregarded unsaturated adsorption conditions.A conceptual model is presented predicting an interparticle threshold spacing below which the impact of the polyelectrolyte binding surface on colloidal arrangement, degree of ordering and coverage may be observed. This discussion discloses the key interplay between the critical working parameters (mainly deposition times of PDDA and colloids as well as salt-induced screening of the intercolloid repulsion) allowing optimal design of colloidal arrangements in terms of order, homogeneity and coverage. In this respect, the occurrence of correlated disorder with respect to disordered arrangements is rigorously characterized by quoting a periodicity-like length associated to the real colloidal distributions.Finally, we perform optical and sensing characterization of metal nanohole distributions with tailored short-range ordering fabricated by the MNL-CL protocol.

Keywords

• Monolayer colloidal lithography protocol
• Threshold interparticle-spacing model
• Autocorrelation analysis
• Salt-related degraded ordering
• Refractive index sensing