Thyalkoid-Based Bio-Solar Cells

Thylakoid bio-solar cells have been developed previously which are capable of direct solar energy conversion through photosynthesis. However, the current output of these cells is quite small compared to mediated systems. Several methods have been implemented to improve the performance. Incorporation of fluorescent carbon quantum dots leads to an increase in photocurrent generation. The conductive quantum dots allow for greater transfer of electrons. Additionally, the quantum dots absorb at wavelengths not necessary for photosynthesis but emit light at wavelengths at which the photosystems of the thylakoids absorb. This makes it possible for the electrodes to use more of the light spectrum.  A second method involved the intercalation of conjugated oligoelectrolytes into the thylakoid membrane. These molecules allow for greater electron transfer through the membrane which decreases the resistance in the thylakoid bio-solar cell. Additionally, the photocurrent produced by the thylakoid electrodes increased as well.  A third method involves separating thylakoids into stacked regions (grana) and non-stacked regions (stroma) which have very different composition of photosynthetic components. Electrodes modified with stroma thylakoids give much larger currents, up to three times larger than full thylakoid membranes.