Applying universal scaling laws to identify the best molecular design paradigms for second-order nonlinear optics

TL;DR

This paper uses universal scaling laws and fundamental limits to identify molecular classes with the highest second-order nonlinear optical responses, guiding the design of superior nonlinear optical materials.

Contribution

It introduces a normalization method and new figures of merit to classify molecular scaling behaviors, identifying promising super-scaling molecular paradigms for nonlinear optics.

Findings

Three molecular classes identified: sub-scaling, nominal-scaling, super-scaling.

Super-scaling homologues maximize nonlinear response with increased size.

Best super-scaling paradigms from literature data highlight traits for new material design.

Abstract

We apply scaling and the theory of the fundamental limits of the second-order molecular susceptibility to identify material classes with ultralarge nonlinear-optical response. Size effects are removed by normalizing all nonlinearities to get intrinsic values so that the scaling behavior of a series of molecular homologues can be determined. Several new figures of merit are proposed that quantify the desirable properties for molecules that can be designed by adding a sequence of repeat units, and used in the assessment of the data. Three molecular classes are found. They are characterized by sub-scaling, nominal scaling, or super-scaling. Super-scaling homologues most efficiently take advantage of increased size. We apply our approach to data currently available in the literature to identify the best super-scaling molecular paradigms with the aim of identifying desirable traits of new materials.