Here at HEXAPOLIS, we have talked quite a bit about the potential of solar power. Remember the UCSD-designed composite nanomaterial that is capable of capturing the sun’s energy with a whopping 90-percent efficiency? Last month, we discussed how perovskite nanowires can greatly enhance the power conversion efficiency of photovoltaics. Well this time around, a team of scientists, working at the Hong Kong University of Science and Technology(HKUST), has developed an ingenious “nanobowl” solar concentrator that can be used in the case of organic photovoltaic (OPV).

The function of concentrated solar power (CSP) systems is to make PV cells more efficient, by focusing larger amounts of the incident sunlight onto a small area. In the research, published in the Science Bulletin journal, the scientists have successfully integrated the CSP technology into organic photovoltaics. So far, majority of the OPV devices contain a glass substrate, along with indium tin oxide electrodes. However, one major problem with this design is the fact that using ITO electrodes actually lowers the efficiency of the OPVs. Furthermore, the cells usually lack sufficient flexibility.

In an attempt to completely eliminate the ITO electrodes from the OPV design, the researchers have developed an incredibly innovative “nanobowl” solar concentrator using cheap and widely available aluminium foil. An exceptional conductor of electricity, aluminium is known for being extremely flexible, easy-to-manufacture and also inexpensive. However unlike the perfectly leveled surface of the glass substrate, the aluminium foil’s surface lacks the smoothness needed to add a uniformly thick layer of organic semiconductor. Instead. the Hong Kong-based scientists installed the nanobowl-shaped optical concentrators on top of the aluminium foil substrate, by means of a chemical process.

Upon successful installation, the nanosized optical concentrators were able to greatly enhance the absorption of incident solar energy. As a whole, the nanobowl solar concentrator-fitted OPV exhibited an impressive 28-percent increase in its conversion efficiency. According to the scientists, the improvement in the OPV’s performance is due to the high photon-absorbing capacity of the nanobowls.

Via: IEEE Spectrum