In order to surpass the Shockley-Queisser limit on power conversion efficiency, schemes to manipulate high- and low-energy photons must be developed. In this talk, I will describe our use of crystal engineering techniques to enhance the singlet fission process, where one high-energy singlet exciton is converted into two lower-energy triplet excitons. Structural modifications that enhance and accelerate this process will be described, along with approaches to harvest the 'dark' triplet states formed by the fission process. I will also describe our search for new chromophore systems that allow triplet-triplet annihilation, which is a process where very low energy triplet excitons, too low in energy to be harvested by Si-based photovoltaics, can be combined into a higher energy photon that is able to be absorbed.

In order to surpass the Shockley-Queisser limit on power conversion efficiency, schemes to manipulate high- and low-energy photons must be developed. In this talk, I will describe our use of crystal engineering techniques to enhance the singlet fission process, where one high-energy singlet exciton is converted into two lower-energy triplet excitons. Structural modifications that enhance and accelerate this process will be described, along with approaches to harvest the 'dark' triplet states formed by the fission process. I will also describe our search for new chromophore systems that allow triplet-triplet annihilation, which is a process where very low energy triplet excitons, too low in energy to be harvested by Si-based photovoltaics, can be combined into a higher energy photon that is able to be absorbed.