Employing a Photosynthetic Antenna Complex to Interfacial Electron Transfer on ZnO Quantum Dot

Photosynthetic antenna complexes exhibit unidirectional energy-transport phenomena, which make them potential photosensitizers in interfacial electron-transfer processes. In the present study, we show the antenna function of phycocyanin-allophycocyanin (PC-APC) complex using transient emission and absorption spectroscopy. Interfacial electron-transfer dynamics in the PC-APC complex sensitized ZnO semiconductor quantum dot material is compared in native and denatured conditions. The downhill sequential energy transfer from a peripheral phycocyanin disk to a core allophycocyanin disk opens a new electron injection pathway from the allophycocyanin disk in addition to primary electron injection from directly photoexcited phycocyanin disk. Further, the large association of phycocayanobilin chromophores in PC-APC conjugates stabilizes the positive charge within the sensitizer, which leads to slower charge recombination in comparison to that in denatured condition. This study displays the antenna function of energy-efficient biomolecules in favor of better charge separation across the semiconductor interface.