Researchers from the University of Rome Tor Vergata's Centre for Hybrid and Organic Solar Energy (CHOSE), IMEC and EPFL have reported on a solar module with an efficiency of 20.72%, based on tin oxide (SnO2) as an electron transport layer, an organometal halide perovskite layer, organic halide salt phenethylammonium iodide (PEAI) as a passivation agent, and Spiro-OMeTAD as the hole transport layer (HTL).
The international research team presented its low-temperature planar perovskite module with an n'i'p architecture, an aperture area of 11'cm2, and a geometrical fill factor of 91%.
The module was built with 0.09 square-centimeter solar cells. The perovskite solution was deposited at 2,000 rpm with 10 seconds ramp-up to fully cover the substrate without persisting at this speed to prevent the dimethyl sulfoxide (DMSO) solvent from sticking onto the substrate.
'This is a very crucial point, because DMSO was trapped during film formation and formed voids at perovskite-substrate interface, as it has been recently demonstrated for a different p'i'n architecture,' the scientists said. 'Moreover, to avoid cracks on the perovskite film, it is very crucial that the velocity of the antisolvent dripping and the distance between substrate and pipet tip.'
The solar module achieved a maximum power conversion efficiency of 19.11% and a stabilized efficiency of 18.7%.
'The reported simple and reproducible method represents an outstanding baseline to be transferred to large-area modules (size â¥100 cm 2 ) by scalable full fabrication procedure out of glove box,' the researchers concluded.