Two Layers Are Better Than One for Efficient Solar Cells – Affordable, Thin Film Solar Cells With 34% Efficiency - SciTechDaily

Solar cells have come a long way, but inexpensive, thin film solar cells are still far behind more expensive, crystalline solar cells in efficiency.

Now, a team of researchers suggests that using two thin films of different materials may be the way to go to create affordable, thin film cells with about 34% efficiency.

“Ten years ago I knew very little about solar cells, but it became clear to me they were very important,” said Akhlesh Lakhtakia, Evan Pugh University Professor and Charles Godfrey Binder Professor of Engineering Science and Mechanics, Penn State.

Investigating the field, he found that researchers approached solar cells from two sides, the optical side — looking on how the sun’s light is collected — and the electrical side — looking at how the collected sunlight is converted into electricity.

“I decided to create a model in which both electrical and optical aspects will be treated equally,” said Lakhtakia.

The problem, he said, was that the mathematical structure of optimizing the optical and the electrical are very different.

Different materials react to and convert different wavelengths of light.

That special way was to use two different absorbent materials in two different thin films.

These two materials work in a solar cell because the structure of both materials is the same.

They have roughly the same lattice structure, so they can be grown one on top of the other, and they absorb different frequencies of the spectrum so they should increase efficiency, according to Lakhtakia.

“Together they produced a solar cell with 34% efficiency.

This creates a new solar cell architecture — layer upon layer.

Reference: “Double-absorber thin-film solar cell with 34% efficiency” by Faiz Ahmad, Akhlesh Lakhtakia and Peter B?

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