WHAT ARE INVISIBLE SOLAR CELLS?

 

A fully transparent solar cell can be made - a new study led by scientists from Incheon National University in Korea.

The first transparent solar cell is demonstrated by an international team of researchers, led by Prof. Joondong Kim from Korea,. in Journal of Power Sources.

 Their pioneering technique breaks on a specific part of the solar cell: the heterojunction, made up of thin films of materials accountable for absorbing light. The researchers were able to generate an efficient, transparent solar cell by combining the exclusive properties of titanium dioxide and nickel oxide semiconductors.

After the Paris climate agreement, everyone is looking for carbon-free future. A vital part of this goal includes the energy conversion from fossil fuels to renewable sources such as solar, hydro, wind and wave energy. Among those, solar energy has been the foremost expectation in the professional community, as the utmost dependable and plentiful energy source on our planet.

Nowadays, solar cells have become economical, more competent, and ecologically friendly. Though, recent solar cells tend to be opaque, which prevents their extensive use and addition into normal materials, constrained to being placed on roofs and in remote solar farms.

Next-generation solar panels could be integrated to windows, buildings, or even mobile phone screens. In a recent study published in Journal of Power Sources, Professor Joondong Kim from the Department of Electrical Engineering at Incheon National University, Korea and his colleagues detail their latest invention: a fully transparent solar cell.

“The unique features of transparent photovoltaic cells could have various applications in human technology,” says Prof. Kim.

The idea of transparent solar cells is well known, but this novel application where scientists have been able to translate this idea into practice is a crucial new finding. At present, the materials making the solar cell opaque are the semiconductor layers, those responsible for capturing light and translating it into an electrical current. Hence, Prof. Kim and his colleagues looked at two potential semiconductor materials, identified by previous researchers for their desirable properties.

The first is titanium dioxide (TiO2), a well-known semiconductor already widely used to make solar cells. On top of its excellent electrical properties, TiO2 is also an environment-friendly and non-toxic material. This material absorbs UV light (a part of the light spectrum invisible to the naked eye) while letting through most of the visible light range. The second material investigated to make this junction was nickel oxide (NiO), another semiconductor known to have high optical transparency. As nickel is one of the mist abundant elements on Earth, and its oxide can easily be manufactured at low industrial temperatures, NiO is also a great material to make eco-friendly cells.

 

Reference: “Transparent photovoltaic cells and self-powered photodetectors by TiO2/NiO heterojunction” by Thanh Tai Nguyen, Malkeshkumar Patel, Sangho Kim, Rameez Ahmad Mir, Junsin Yi, Vinh-Ai Dao and Joondong Kim, 12 September 2020, Journal of Power Sources.