New Way to Larger Perovskite Solar Cells

Perovskites can be used to create light-weight flexible and semi-transparent solar cells ideal for applications in buildings and a variety of urban spaces. (Source: NTU)

Perovskites are materials that have emerged as promising alternatives to silicon in solar cell appli­cations. The material offers power conversion effi­ciencies similar to silicon solar cells but can also be used to create light-weight flexible and semi-trans­parent cells ideal for applications in buildings and a variety of urban spaces. Perovskite techno­logies are progressing rapidly towards indus­trialisation, with stability and scala­bility to larger sizes seen by researchers as the last hurdles to overcome.

Now, researchers at Nanyang Techno­logical University in Singa­pore report that they have adopted a common industrial coating technique – thermal co-evaporation – and found that it can fabri­cate solar cell modules of 21 square centi­meters size with record power conversion effi­ciencies of 18.1 per cent. These are the highest recorded values reported for scalable perovskite solar cells.

Annalisa Bruno, Senior Scientist at the Energy Research Institute explained the roadblock in the large-scale adoption of perovskite solar modules. “The best-performing perovskite solar cells have so far been realised in the labora­tory at sizes much smaller than 1 square centimeter, using spin-coating. However, when used on a large surface, the method results in perovskite solar cells with lower power conversion effi­ciencies. This is due to the intrinsic limi­tations that include defects and lack of uniformity over large areas, making it challenging for industrial fabrication methods”, she said.

“By using thermal eva­poration to form the perovskite layer, our team success­fully developed perovskite solar cells with the highest recorded power conversion efficiency reported for modules larger than 10 square centimeters. Our work demons­trates the compa­tibility of perovskite technology with industrial processes, and its potential for market entry. This is good news for Singapore, which is looking to ramp up the use of solar energy for its power needs”, she said.

Her colleague Li Jia said, “We have demons­trated the excellent scalability of co-evaporated perovskite solar cells for the first time. This step will acce­lerate the transition of this technology from labora­tory to industry.” Utilising the same technique, the researchers then fabricated coloured semi-trans­parent versions of the perovskite solar cells and mini modules, which achieved similar measures of power conversion effi­ciency across a whole range of different colours.

These results demonstrate the versa­tility of the thermal eva­poration method in producing a variety of perovskite-based solar devices for a variety of opto­electronic appli­cations. Subodh Mhaisalkar said the findings open doors for Singa­pore and urban environments in other countries to harness the power of sunlight more efficiently than ever before. “The solar mini modules can be used on facades and windows in sky­scrapers, which is not possible with current silicon solar panels as they are opaque and block light. Building owners will be able to incor­porate semi-transparent coloured solar cells in the archi­tectural designs to harvest even more solar energy without compromising the aesthetic qualities of their buildings”, Mhaisalkar said.

Nripan Mathews from the School of Materials Science & Engineering at NTU said, “This work highlights the breadth and depth of perovskite research at NTU. There is no other team in the world which pursues the various possi­bilities that perovskites provide under one roof. From large area solar cells for buildings, high effi­ciency perovskite-silicon tandem devices, to light emitting diodes – our team is inspired to tackle the key challenges involved to expedite techno­logical deployment.”

Providing another view, Armin Aberle, Chief Executive Officer of the Solar Energy Research Institute of Singapore (SERIS) at the National Univer­sity of Singapore (NUS) said, “This work represents the first demonstration of highly efficient large-area perovskite solar cells fabricated by an indus­trially compatible process. We are working closely with NTU in the future development of 30% efficient perovskite-on-silicon tandem solar cells in Singapore.” The team is now looking at integrating perovskite and silicon solar cells to create a tandem solar cell. Such a confi­guration fabricated using cost-effective and scalable processes can sub­stantially increase the solar elec­tricity production per unit area while keeping production costs low. (Source: NTU)

Reference: J. Li et al.: Highly Efficient Thermally Co-evaporated Perovskite Solar Cells and Mini-modules, Joule 4, 1035 (2020); DOI: DOI: 10.1016/j.joule.2020.03.005

Link: Energy Research Institute ERI@N, Nanyang Technological University, Singapore, Singapore

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