Scientists make game-changing breakthrough that could unlock low-cost energy source: 'Our work delivers promising guidelines'

Researchers have uncovered a promising new direction for solar panel development. By using inorganic hole transport layers, the study's authors hope to provide a path to developing new, more efficient thin-film solar panels. 

The American Solar Energy Society describes thin film as "the future of the solar industry" because it costs less to produce, requires less material, and is easy to manufacture. As the name suggests, thin-film solar panels are about 350 times thinner than mono or polycrystalline panels. They're not as efficient or long-lasting as their thicker cousins, but that could soon change. 

Experiments on different materials have yielded promising results. Yet, as one of the study authors noted, writing in Tech Xplore, some of the existing version of thin-film materials' rarity and toxicity hold them back, while the alternative compounds offering promise do not have those drawbacks. Yet they also do not yet show sufficient efficiency to compete with conventional solar panels. 

A compound called Cu2SrSnS4, or CSTS, is made of copper, strontium, tin, and sulfur. The advantage of CSTS is that it's nontoxic and abundant. However, as the researchers point out, it's still an emerging technology with low power conversion efficiency. That's where the inorganic hole transport layers come in.

In simple terms, the hole transport layer, or HTL, is a specialized material used in solar cells to allow the movement of positive charges (holes) absorbed by light. The study found that oxide-based HTL was a cut above with a power conversion efficiency of about 18.5%, a massive upgrade on the CSTS' PCE of 0.6%, per the Tech Xplore report.

So, what does this mean for the future of solar power? For one, it could further reduce the cost and offer a great deal of flexibility. 

The problematic supply chain is another key problem with solar panels that holds back wider adoption by the global community. Most solar panels today rely on polysilicon, which is overwhelmingly produced in the Xinjiang autonomous region of China. Allegations of forced labor have led some governments to blacklist components sourced from the area. 

This emerging tech is still likely a long way away from influencing the home solar market, and in the meantime regardless, solar is booming. According to Ember's annual review, solar energy grew by 29% in 2024, making it the world's fastest-growing energy source for the 20th straight year. 

The new research could one day help increase that momentum by making solar panels cheaper and easier to manufacture with ethically sourced materials, though in the meantime, solar panels from reputable installers — through third-party companies offering reviews and advice like EnergySage — are a great way to start getting a massive return on investment by tapping into free energy from the sun. EnergySage can also help with securing federal tax credits of around $10,000, depending on the size of the project. 

As one of the study's authors, Latha Marasamy, wrote for Tech Xplore: "Our work delivers promising guidelines … to understand the importance of HTL in improving the efficiency of solar cells."

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