Dec 16 2019
Transparent solar cells (TSCs) are novel devices that integrate the benefits of visible transparency and the conversion of light into electricity. These devices offer potential valuable applications—for example, they can be integrated into portable electronics, vehicles, or buildings.
Image Credit: Martin D. Vonka
As a result, factors such as flexibility, color-perception, as well as efficiency are significant. Although existing TSCs are mostly based on perovskites, organics, amorphous Si, and dyes, the rigidity or color-tinted transparent nature of TSCs considerably restricts the utility of the subsequent TSCs for real-world applications.
In the latest study published in the Light Science & Application journal, researchers from the Department of Materials Science and Engineering, Ulsan National Institute of Science and Technology, Republic of Korea, in association with colleagues, have created TSCs that are efficient, flexible, and have color-neutrality.
On the basis of silicon microwires integrated into the transparent polymer matrix, the researchers demonstrated solar cells that were flexible, transparent, and even stretchable. The freestanding film was effectively used for fabricating a block of transparent solar cells.
A transparent conductive film is formed at the base of the device. A heterojunction between the p-type polymeric semiconductor and the n-type Si is created at the top portion of the device. The spacing between the microwires can be adjusted to tune the transparency of the devices from approximately 10% to 55%.
In addition, under the bending state or after the cyclic bending test, the performance of the device was sustained without any considerable decrease. This indicates that the TSCs have exceptional flexibility. The transparent and stretchable freestanding form of microwire array/polymer composites film, demonstrated in this work, shows promise for upcoming TSCs.
But TSCs have an inevitable trade-off between the light admission and the energy generation. Hence, on the basis of the criteria for TSCs, the efficiency is inevitably compromised to realize transparency. This makes it difficult to obtain high-performance TSCs.
To resolve this problem, the researchers suggested a new method to achieve high-performance TSCs.
According to the researchers:
Basically, the solar cells can generate the electricity from the absorbed light. Therefore, attaining the high performance as maintaining the transparency is very challenging. We revealed absorption mechanism inside Si microwire-array and developed the new morphology of microwire which can manipulate the path of light.
They continued, “As a result, we successfully enhanced light absorption which can contribute to the light-generated-current in the transparent solar cells maintaining the transparency.”
The transparent solar cell based on the freestanding film with advanced light-absorption technique shows the power conversion efficiency over 8 % at 10 % of visible transparency, which are comparable to state-of-the-art neutral-colour transparent solar cells based on organics and perovskites.
Department of Materials Science and Engineering, Ulsan National Institute of Science and Technology, Republic of Korea
“Moreover, the devices are based on the Si wafer already verified and widely used in the Si solar cell market. Therefore, this robust, ultra-light and flexible platform is feasible and promising as a commercialized transparent solar cell for practical application in the future,” predicted the researchers.