Light-induced processes in organic chemistry: Decarbonylations in crystals, quantum tunneling, and solar cells.

摘要

Sunlight is the most abundant source of energy with vast potential to be employed in organic chemical transformations and in physical processes. Within our interest to understand how light can be exploited in organic synthesis and materials science, we devoted our research efforts to these areas. The thesis includes results on: (i) theoretical investigations of the photochemistry of ketones and (ii) solar cell device optimizations using organic polymers as electron donors blended with a fullerene derivative as an electron acceptor.; i. Pollution of the ecosystem has triggered concern worldwide, leading to the pursuit of Green Chemistry. Many reactions, however, require the use of excessive amounts of solvents, metal catalysts, and other chemicals that may be harmful to the environment. A rather unexplored methodology involves light-induced chemical transformations in organic crystalline media. Even more challenging, the power to predict and engineer these photochemical reactions in the solid state is a concept in need of exploration, which this thesis to addresses. Chapter 1 includes an overview of reactivity and the role or reactive intermediates in crystalline media. Chapters 2 and 3 discuss computational experiments that uncovered the thermochemical parameters of photo-decarbonylations of ketones, and the development of a simple model to predict reactivity in the solid state. Chapter 4 is devoted to studies involving the design of rigid molecules capable of undergoing hydrogen tunneling reactions at cryogenic temperatures upon photo-excitation.; ii. In materials science, the lack of renewable energy resources has been the subject of intensive research, given our current status of global warming and extreme climate changes. More than one decade ago, organic materials were introduced in solar cell devices. Being at a rather infant stage, many efforts have been devoted to increase their efficiency, due to the high potential for low-cost production, among other advantages. Three polymers possessing a thiophene backbone were introduced in solar cell devices for their unique characteristics. Chapters 5, 6, and 7 include our studies of device performance using these different polymers as electron donors and employing a fullerene derivative as an electron acceptor in bulk heterojunction solar cells.