Georgia Institute of Technology

Dr. Reichmanis’ research interests include the chemistry, properties and applications of materials technologies for electronic and photonic applications, with particular focus on polymeric and nanostructured materials for advanced technologies.

Current research topics in the Reichmanis group include:

Design, synthesis and characterization of organic semiconductors

Although significant progress has been made, organic semiconducting polymers typically have low charge carrier mobility, low oxidation stability and a relatively large bandgap relative to their inorganic counterparts. From a molecular perspective, intra- and inter-molecular π-orbital overlap (or π – π stacking) determines the charge transport performance. We are engaged in studying the effects of molecular co-planarity, intra-molecular charge transport and electron-withdrawing substitution on the optical and electronic properties of candidate polymers with the aim of facilitating their field-effect charge transport and photovoltaic performance.

Fundamental understanding of structure-property relations in organic semiconductor thin films

Subtle micro-/macro-structural changes in organic semiconductor thin film architecture dominates the electrical properties of the material. We are developing efficient processing techniques to manipulate and control the micro-/macro-structure of the thin films, and investigating how the resultant structure impacts macroscopic charge transport within the material.  Techniques such as absorption and vibrational spectroscopy, atomic force microscopy, x-ray diffraction and electrical measurements of thin films have been employed to understand relationships between molecular structure, thin film architecture, optical properties and macroscopic charge transport in organic/polymer/hybrid semiconductor materials.  Efforts to understand the impact of interfaces are also in progress.

Processing dependent morphology-performance relationships in organic photovoltaic cells

Phase separation and crystallization into desirable bulk heterojunction morphologies through process optimization are effective ways to increase the power-conversion efficiency of an organic photovoltaic cell. Process parameters such as solvent boiling point/volatility, solubility parameters of both the active materials and deposition solvents, thermal and/or solvent vapor annealing have a profound impact on the morphology of the active layer, which influences solar cell performance. We are engaged in investigating how process parameters affect blend morphology and thus device performance. For instance, Hansen solubility parameters and Spano’s model are employed to systematically understand the effects of processing on the morphology and thus optoelectronic properties of the photovoltaic cells.