High Efficiency Ultrathin Solar Cell Developed by UK based Researchers

Researchers at Imperial College London and University College London (UCL) claim to have found a novel technique to enable record-breaking power conversion efficiency in solar cells that are at least 100 times thinner than the conventional solar cells.

The usual silicon based solar cells’ fabrication is often expensive, energy-demanding, heavy and bulky in nature. Also, the ultrathin film solar cells created until now are made often with toxic elements like lead and cadmium.

In the new research, AgBiS2 nanocrystals have been employed as the new material to create ultrathin cells which are non-toxic, abundantly found in earth and the complete solution is low cost. These nanocrystals can be integrated into ultrathin solar cells and prove to be highly stable that avoids degradation of the cell.

The team at Imperial College London and UCL have formulated a novel technique in which the power conversion efficiency in the ultrathin material is more than 9.1%.

The Technology

The research team had first created a theoretical model of AgBiS2 where they predicted that controlled distribution of silver and bismuth atoms in the nanocrystals can heighten the light absorption and increase efficiency of the solar cells. Then a layer of nanocrystals was engineered in the cell through a technique called ‘Cation Disorder Engineering.’

In this method the material is heated at 150°C to allow the silver and bismuth atoms to be evenly spread throughout the nanocrystals. This is done to allow stronger absorption of light. Hence, through delicate deposition of AgBiS2 nanocrystals layer-by-layer, a novel cell which is 100 times thinner than current commercial solar cells is achieved. The new ultrathin cell has broken the previous record of 6.3% when under the artificial sunlight power conversion efficiency was found beyond 9.1%.

The experiments also found that AgBiS2 has absorption capacity 5-10 times more than any other material that is presently employed in solar technology. Sen Kavanagh mentions, “The combination of low cost, non-toxicity and good efficiency, as well as its ultrathin structure, means that AgBiS2 could support a revolution in solar power.”

His senior and co-author of the study, Professor Aron Walsh stated, “Emerging solar energy technologies have faced longstanding issues related to metal distributions in the active materials. Our findings give hope that disorder can be controlled and that efficient solar energy conversion is possible. I expect to see a more diverse range of commercial solar cells in the near future.”

The team also says that the commercial application of the new ultrathin cells made with the novel technology is that huge solar devices can be created in windows, car roofs and even clothes as they can be 3D printed.