Solar energy has long been considered the most sustainable option for replacing our dependence on fossil fuels, but technologies for converting solar energy into electricity must be both efficient and inexpensive.

Scientists from the Energy Materials and Surface Sciences Unit at the Okinawa Institute of Science and Technology Graduate University (OIST) believe they’ve found a winning formula in a new method to fabricate low-cost high-efficiency solar cells. Prof. Yabing Qi and his team from OIST in collaboration with Prof. Shengzhong Liu from Shaanxi Normal University, China, developed the cells using the materials and compounds that mimic the crystalline structure of the naturally occurring mineral perovskite. They describe their technique in a study published in the journal Nature Communications.

In what Prof. Qi refers to as “the golden triangle,” solar cell technologies need to fulfill three conditions to be worth commercializing: their conversion rate of sunlight into electricity must be high, they must be inexpensive to produce, and they must have a long lifespan. Today, most commercial solar cells are made from crystalline silicon, which has a relatively high efficiency of around 22%. Though silicon, the raw material for these solar cells, is abundant, processing it tends to be complex and shoots up the manufacturing costs, making the finished product expensive.

New insight into how a certain class of photovoltaic materials allows efficient conversion of sunlight into electricity could set up these materials to replace traditional silicon solar cells. A study by researchers at Penn State reveals the unique properties of these inexpensive and quick-to-produce halide perovskites, information that will guide the development of next generation solar cells. The study appears September 27 in the journal Chem.

“Since the development of silicon solar cells, which today can be found on rooftops and roadsides, researchers have sought new types of photovoltaic materials that are easier to process into solar cells,” said John Asbury, associate professor of chemistry at Penn State and senior author of the study. “This is because construction of silicon solar cells is complex and hard to scale-up to the level that would be needed for them to generate even 10 percent of our total demand for electricity.”

Because of these complications, researchers have been searching for less expensive alternatives to silicon solar cells that can be processed more quickly. They are particularly interested in materials that can be processed using a technique called roll-to-roll manufacturing, a technique similar to those used to print newspapers that enables low-cost, high-volume production. Such materials must be processed from solution, like ink printed on a page.