Paul Stavrinou

Abstract:

The ability to propagate light within a structure comprising a controlled spatial distribution of the refractive index n prompted the telecommunications revolution of the 20th century. More recently, progress with exploiting the flow of light has led to a broad range of light‐ and heat‐management tools, as well as novel quantum devices. This perspective discusses a new versatile class of optical materials based on molecular hybrids of metal oxide hydrates and commodity polymers, such as poly(vinyl alcohol). These fascinating, easy‐to‐produce materials are examined, and their processing into useful architectures such as photonic crystals is reviewed, with a focus on thin‐film optics. Their potential in other areas is also assessed, for instance, for the fabrication of optical microcavities that allow the formation of exciton‐polaritons, enabling studies on strong light‐matter interactions. Generally, these molecular hybrids open future opportunities in applications like optics, photonics, quantum devices, catalysis, and beyond.

Abstract:

One grand challenge for printed organic electronics is the development of a knowledge platform that describes how polymer semiconductors assemble from solution, which requires a unified picture of the complex interplay of polymer solubility, mass transport, nucleation and, e.g., vitrification. One crucial aspect, thereby, is aggregate formation, i.e., the development of electronic coupling between adjacent chain segments. Here, it is shown that the critical aggregation temperatures in solution (no solvent evaporation allowed) and during film formation (solvent evaporation occurring) are excellent pointers to i) establish reliable criteria for polymer assembly into desired aggregates, and ii) advance mechanistic understanding of the overall polymer assembly. Indeed, important insights are provided on why aggregation occurs via a 1- or 2-step process depending on polymer solubility, deposition temperature and solvent evaporation rate; and the selection of deposition temperatures for specific scenarios (e.g., good vs bad solvent) is demystified. Collectively, it is demonstrated that relatively straightforward, concurrent in situ time-resolved absorbance and photoluminescence spectroscopies to monitor aggregate formation lead to highly useful and broadly applicable criteria for processing functional plastics. In turn, improved control over their properties and device performance can be obtained toward manufacturing sensors, energy-harvesting devices and, e.g., bioelectronics systems at high yield.