Exceeded silicon Shockley-Quiesser limit
New world record in the field of solar energy. The Longi Green Energy Technology has made the photovoltaic perovskite silicon tandem a further step forward, reaching a conversion efficiency of light to electricity of 33.9 percent. It is the world’s highest certified value for this technology. The confirmation comes from the latest analysis of the National Renewable Energy Laboratory (NREL) of the United States, the Best Research-Cell Efficiency Chart. The graph not only reports the yield value but also shows how the CSI-perovskite solar cells of longitude represent the most efficient product ever made with crystalline silicon. To exceed the so-called Shockley-Queisser limit of single junction Si cells.
The record, which subtracts King Abdullah University of Science & Technology (KAUST) from the record recorded in May this year, is the result of tight work by the Chinese giant to improve design and performance. The result is a monolithic double junction cell one square centimeter wide and an open circuit voltage (Voc) of 1.966 V.
Photovoltaic tandem perovskite silicon
The photovoltaic perovskite silicon tandem offers between its layers a great promise: it is one of the most “simple” ways to increase yield without the use of concentrators or expensive materials. The idea behind the multi-junction approach is to combine semiconductors with different band gaps in a single device, to expand the portion of exploitable solar spectrum. In this case, the silicon band gap is 1.12 EV, and that of perovskite is about 1.7 ev. In other words, silicon can efficiently use low-energy photons and perovskite high-energy photons. Together they greatly advance the theoretical limit of efficiency – up to 43 percent – significantly improving the yield of photovoltaic.
For the Chinese company, it is a goal to be pursued at all costs. “The emergence of tandem crystalline-perovskite silicon technology has opened a new path for the development of next-generation high-efficiency photovoltaic cell technology,” explained Longitude in a press release. “This means that the same area, absorbing the same light, can emit more electricity“. The company is not new to records in this segment. In fact, it has set a world record 15 times since April 2021. And the race is just beginning.