The most vexing physical challenges in artificial photosynthesis are (1) the weak intrinsic propensity of chromophores to absorb photons and (2) the unfavorable kinetics for producing free carriers with high yield, once an electronic excited state is formed. My seminar focuses on understanding some of the foundational constraints on these key processes, with the aim of using this understanding to develop structures with enhanced performance. We have examined the distribution of oscillator strengths in molecules as a function of frequency to understand why only a few percent of the integrated oscillator strength guaranteed by the Thomas-Reiche-Kuhn sum rule is available for solar energy harvesting. With this understanding, we are exploring schemes to focus oscillator strength into specific frequency windows. On the topic of charge flow and electron transfer control, we have established a theoretical framework to understand how infra-red excitation may be used to manipulate electron-transfer kinetics. The latter studies may provide schemes to accelerate or slow charge transport on demand.