Hydrogen annealing approach sets new efficiency record for kesterite solar cells

Photovoltaics (PVs), units that may convert daylight into electrical energy, have gotten more and more widespread and extra individuals worldwide at the moment are counting on them to generate electrical energy. Renewable power engineers worldwide are working to establish supplies and processes that would assist to additional cut back the prices of photo voltaic applied sciences, whereas additional boosting their power-conversion-efficiencies (PCEs).

A promising materials for the event of PVs is wide-bandgap kesterite Cu₂ZnSnS₄ (CZTS), a semiconductor that reveals a big power hole and will thus take in mild extra effectively. In distinction with silicon, which is at the moment the first materials used to manufacture PV know-how, CZTS is non-toxic and fabricated from parts which can be plentiful on Earth. Thus, it might be used to create extra sustainable and reasonably priced photo voltaic cells.

Regardless of their benefits, CZTS photo voltaic cells have to date exhibited considerably decrease efficiencies than their silicon counterparts, reaching a most of 11%. Their restricted efficiency is in nice half attributable to a course of often called service recombination, which entails the recombination of photo-generated electrons and holes earlier than they are often captured to generate electrical energy.

Researchers at College of New South Wales in Sydney explored the potential for mitigating the consequences of service recombination in wide-bandgap kesterite photo voltaic cells utilizing a way often called hydrogen annealing.

Their paperrevealed in Nature Powerreveals that this method may assist to enhance these photo voltaic applied sciences’ service assortment, by redistributing oxygen and sodium in CZTS layers.

“Our work was inspired by the need to identify a sustainable, low-cost, and environmentally friendly material for next-generation solar technologies,” Kaiwen Solar, senior writer of the paper, advised Tech Xplore.

“CZTS is a particularly promising candidate as the top cell in tandem solar cell architectures due to its tunable bandgap, stability, and use of earth-abundant, non-toxic elements. However, a key challenge has been improving this material’s carrier collection efficiency.”

The primary goal of this current examine was to indicate that hydrogen annealing, a way that entails heating up units in a hydrogen-containing environment, may assist to spice up the efficiencies of CZTS. To attain this, the researchers devised a easy and scalable methodology to anneal CZTS in a hydrogen-containing atmosphere.

“Hydrogen plays a crucial role in our method, by redistributing sodium within the material and passivating defects, particularly near the absorber surface,” defined Solar.

“This process significantly enhances carrier transport and collection, key factors for achieving high-performance devices. By improving these properties, our approach strengthens CZTS’s position as a practical and cost-effective top cell material in tandem solar cells, capable of efficiently pairing with silicon for broader solar spectrum utilization.”

As a part of their examine, Solar and his colleagues utilized their proposed hydrogen annealing methodology to a cadmium-free CZTS photo voltaic cell. Notably, they discovered that this method boosted the photo voltaic cell’s efficiency, yielding a report effectivity of 11.4%.

“Our proposed technique is not only specific to CZTS but has also shown promising results in other thin-film solar cell materialssuch as CIGS,” stated Solar. “Practically, it demonstrates how wide-bandgap CZTS, with its low cost, stability, and environmental friendliness, could serve as an excellent top cell candidate in tandem architectures, paving the way for more efficient and sustainable solar energy solutions.”

The current paper by Solar and his colleagues introduces a easy and efficient approach to manage the distribution of sodium in CZTS, which might in flip improve the service assortment effectivity of CZTS-based photo voltaic cells. Sooner or later, their proposed method might be utilized to different wide-bandgap kesterite PVs, doubtlessly contributing to their future deployment in real-world settings.

“Our future analysis goals to push the effectivity of wide-bandgap CZTS solar cells past the 15% benchmark whereas sustaining their environmental and financial benefits,” added Solar. “This includes refining the hydrogen annealing process and exploring other techniques to further optimize the material’s optoelectronic properties.”

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