Perovskite solar cells take a dip into large-scale production

A new, simpler solution process for fabricating stable perovskite solar cells overcomes a key bottleneck to the large-scale production and commercialization of this promising renewable-energy technology, which has remained tantalizingly out of reach for more than a decade. "Our work paves the way for low-cost, high-throughput commercial-scale production of large-scale solar modules in the near future," said Wanyi Nie, a research scientist fellow in the Center of Integrated Nanotechnologies at Los Alamos National Laboratory and corresponding author of a paper on this work in Joule. "We were able to demonstrate the approach through two mini-modules that reached champion levels of converting sunlight to power with greatly extended operational lifetimes. Since this process is facile and low cost, we believe it can be easily adapted to scalable fabrication in industrial settings." The team invented a one-step spin coating method using sulfolane, a liquid solvent. The new process allowed the team, a collaboration between researchers at Los Alamos and the National Taiwan University (NTU), to produce high-yield, large-area photovoltaic devices that are highly efficient at generating electricity from sunlight. These perovskite solar cells also have a long operational lifetime. "We are excited about this achievement," said Leeyih Wang, the principal investigator in the NTU group and one of the corresponding authors, "this is a new synthetic route that is widely applicable in the rich perovskite material family." "We have implemented new chemistry to push it towards a technologically relevant demonstration," said Hsin-Hsiang Huang, a graduate student at NTU and the first author of the paper. Perovskite photovoltaics, seen as a viable competitor to the familiar silicon-based photovoltaics, have been a highly anticipated emerging technology over the past decade. But commercialization has been stymied by the lack of a solution to the field's grand challenge: scaling up production of high-efficiency perovskite solar cell modules from the bench-top to the factory floor. The Joule paper shows a new route to fabrication, by introducing sulfolane as an additive to the perovskite precursor, or the liquid material that creates the perovskite crystal through a chemical reaction. As in other fabrication methods, that crystal is then deposited on a substrate. Through a simple dipping method, the team was able to deposit a uniform, high-quality perovskite crystalline thin film covering a large active area in two mini-modules, one about 16cm2 and the other nearly 37cm2. Fabricating uniform thin film across the entire area of a photovoltaic module is essential for device performance. The mini-modules achieved power conversion efficiencies of 17.58% and 16.06%, respectively, which are among the top achievable efficiencies reported to date. The power conversion efficiency is a measure of how effectively sunlight is converted into electricity. For other perovskite fabrication methods, one of the major roadblocks to industrial-scale fabrication is their narrow processing window, the time during which the film can be laid down on the substrate. To get a uniform crystalline film that's well bonded to the layer below it, the deposition process has to be strictly controlled within a matter of seconds. Using sulfolane in the perovskite precursor extends the processing window from 9 seconds to 90 seconds. This leads to the formation of highly crystalline, compact layers over a large area, which are less dependent on the processing conditions. This sulfolane method can be easily adapted to existing industrial fabrication techniques, helping to pave the path toward commercialization. This story is adapted from material from Los Alamos National Laboratory, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.