Scientists identify new ‘promising’ absorber material for thin-film solar cells

Researchers led by Dartmouth College in the United States have identified zintl-phosphide (BaCd2P2) as a potential new absorber material for thin-film solar cells after conducting a high-throughput (HT) computational screening among 40,000 promising inorganic materials.

“Based on its dopability, this material could be used as a p-type absorber layer for pn junction cells or as an intrinsic absorber layer for p-i-n cells,” researcher Zhenkun Yuan told pv magazine.

The group selected the inorganic materials from the Materials Project database, which is an open-access database describing material properties that can be used to accelerate the development of a given technology by predicting how new materials, both real and hypothetical, can be potentially utilized.

Through the screening, the scientists initially identified materials that offer a suitable band gap, small effective masses, and promising defect properties. “Among these promising candidates, we select the zintl-phosphide (BaCd₂P₂) and explicitly show that the computed nonradiative recombination rates in BaCd₂P₂ are better than or comparable with those in high-efficiency solar absorbers such as the halide perovskites,” they explained.

After identifying the material, the group found that zintl-phosphide can be very stable both in air and water. “You can put it out for six months and it will stay the same,” added the research's corresponding author, Geoffroy Hautier. “When you don't have to worry about moisture and air contamination, that significantly reduces your costs.”

By conducting bright photoluminescence (PL) and time-resolved microwave conductivity (TRMC), it also found the material has a potential energy bandgap of 1.45 eV and a carrier lifetime of up to 30 ns.

“All of these results indicate that BaCd₂P₂ is a promising high-performance solar cell absorber with the potential to open a new avenue in PV for an entire family of Zintl AM₂X₂ solar absorbers, where A and M are +2 ions and X is a pnictogen,” the researchers said.

“We won't have it as a solar panel tomorrow,” added Hautier, “but we think this family of materials is exceptional and worth looking at.”

Their findings were presented in the paper “Discovery of the Zintl-phosphide BaCd₂P₂ as a long carrier lifetime and stable solar absorber,” published in Joule.