PTFE PhD Defense - Nabunkur Deb

Thursday, July 2, 2015

10 a.m.

Room G021, MoSE Building

Committee:

David Bucknall, MSE (Advisor)

Seth Marder, Chemistry

John Reynolds, Chemistry/MSE

Zhiqun Lin, MSE

Elsa Reichmanis, ChBE

TITLE: Morphological studies in polymer fullerene blends

Polymer-fullerene blend systems have found relevance and application in a number of fields including organic photovoltaic devices. While synthesizing new materials with desirable electronic properties is essential to designing better photovoltaic devices, it is equally important to understand the complex phase morphology of these blends and its effect on device performance. Consequently, this knowledge could be used to further design new materials and device architecture for more efficient systems. In particular, this dissertation focuses primarily on the morphology in a series of amorphous as well as semi-crystalline polymer-fullerene blend systems both in bulk and thin films and its relation to device performance. Scattering based techniques have been used to determine in-plane and out-of-plane phase morphology. Morphological parameters derived from these studies have shown possible correlation between fullerene segregation and device performance values. The results of these studies have been used to synthesize a thermo-cross-linkable fullerene acceptor having slower diffusion through the polymer, allowing better control of the polymer-fullerene blend morphology. Consequent effects have been studied on device lifetime and thermal stability and have shown significant improvements.