Towards 'personalised energy' with transparent solar cells

South Korean scientists have put forth an innovative design for high-power transparent solar cells, bringing us closer to a sustainable future with off-grid living. Their study has been published in the journal Nano Energy.

The imminent climate change crisis demands a shift from conventionally used fossil fuels to efficient sources of green energy. This has led to researchers looking into the concept of ‘personalised energy’, which would make onsite energy generation possible. For example, solar cells could possibly be integrated into windows, vehicles, smartphone screens and other everyday products. To this end, scientists have developed ‘transparent photovoltaic’ (TPV) devices that make use of the ‘invisible’ light that falls in the ultraviolet (UV) range — unlike the conventionally dark, opaque solar cells that absorb visible light.

Conventional solar cells can be either ‘wet type’ (solution-based) or ‘dry type’ (made up of metal-oxide semiconductors). Of these, dry-type solar cells are typically more reliable, eco-friendly and cost-effective. Moreover, metal oxides are well suited to make use of the UV light. Now researchers from Incheon National University have come up with an innovative design for a metal-oxide-based TPV device, inserting an ultrathin layer of silicon (Si) between two transparent metal-oxide semiconductors with the goal of developing an efficient TPV device.

“Our aim was to devise a high-power-producing transparent solar cell, by embedding an ultrathin film of amorphous Si between zinc oxide and nickel oxide,” said study leader Professor Joondong Kim.

The team’s novel design has three major advantages. First, it allows for the utilisation of longer-wavelength light (as opposed to bare TPVs). Second, it results in efficient photon collection. Third, it allows for the fast transport of charged particles to the electrodes. Moreover, the design can potentially generate electricity even under low-light situations (for instance, on cloudy or rainy days). The scientists further confirmed the power-generating ability of the device by using it to operate the DC motor of a fan.

Based on these findings, the research team is optimistic that the real-life applicability of this new TPV design will soon be possible. As for potential applications, Prof Kim said the researchers “hope to extend the use of our TPV design to all kinds of material, right from glass buildings to mobile devices like electric cars, smartphones and sensors”.

The team is excited to take their design to the next level, by using innovative materials such as 2D semiconductors, nanocrystals of metal-oxides and sulfide semiconductors. According to Prof Kim, “Our research is essential for a sustainable green future — especially to connect the clean energy system with no or minimal carbon footprint.”

Image courtesy of the study authors.

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