Solar cells made from perovskite, a material that is able to harvest sunlight and convert it to electricity, hold great potential as a replacement for silicon solar cells.
Despite superior performance, efficiency and being cheaper to manufacture, perovskite solar cells have not been commercially manufactured for the consumer market.
Perovskites decompose when they react with moisture and oxygen or when they are exposed to light, heat, or used for an extended time, resulting in concerns that the small amount of lead, a toxic heavy metal, present in perovskite solar cells could pollute the environment when the solar cell is damaged or discarded.
The lead comes from both the perovskite material and a compound used to make a component of the perovskite solar cell, known as the capping layer.
Now, research by scientists from Nanyang Technological University, Singapore (NTU Singapore) and the Institute of Materials Research and Engineering (IMRE) at the Agency for Science, Technology and Research (A*STAR) in Singapore has provided the possibility of capping materials based on non-toxic metals being used in the manufacture of perovskite solar cells.
Their study, published in Nature Energy in February 2023 and led by Professor Sum Tze Chien, Director of the Institute of Advanced Studies at NTU and Associate Dean (Research) of NTU's College of Science, and Professor Lam Yeng Ming, Chair of NTU's School of Materials Science and Engineering, could take perovskite solar cells one step closer to the market.
(Left) The molecular structure of perovskite (blue) with the zinc-based capping layer (green). (Right) The FP process that the researchers used to coat the zinc-based capping layer onto the perovskite layer. Credit: NTU Singapore.
To fabricate the zinc-based capping layer, the researchers dissolved the chemicals and coated the solution onto the perovskite layer in a glovebox. The glovebox protects the perovskite from oxygen and moisture in the environment before it is coated. Credit: NTU Singapore.
The researchers used a vacuum evaporation system to synthesize the remaining layers of the perovskite solar cell, a method commonly used for the fabrication of perovskite solar cells. Credit: NTU Singapore.
(Left) A diagram showing the different layers of the perovskite solar cell capped with the zinc-based capping material fabricated by the researchers. (Right) The dotted green rectangle indicates the active region of the perovskite solar cell that captures sunlight and converts it to electricity. Credit: NTU Singapore.