Research continues in the field of perovskite technology, particularly in tandem applications. While the efficiency achieved in the latest published work in the field has only achieved 13.8% efficiency, MIT-Stanford researchers say that the voltage of 1.65 V was at the top of the range the team had set as a target.
Key to the achievement, report the solar researchers, is the effective tunnel junction achieved in the perovskite-cSi cell. The team used degenerately doped p-type and n-type silicon for the tunnel junction. A titanium-dioxide layer is also used to allow electrons to pass from the perovskite and into the tunnel junction layer before then transferring to the c-Si.
The MIT-Stanford team also used a series connection, helping to achieve the 1.65 V result.
The results were published in the Applied Physics Letters journal.
Jonathan P. Mailoa, a graduate student in MIT’s Photovoltaic Research Laboratory was a co-author on the paper and he acknowledges that efficiency gains will have to be made for perovskite technology to reach its potential. One way to do this is by increasing the quality of c-Si cell.
"Parasitic optical losses in other layers of the multi-junction solar cell devices and predicting their efficiency potentials through simulation will determine whether or not this approach is truly cost effective," Mailoa told Phys.org. The researchers are continuing to work on a solution for an interlayer between PV layers.
"Fortunately, the physical concepts already exist for other types of multi-junction solar cells, so we simply need to find the best interlayer material combination for the perovskite-silicon pair," Mailoa said.