Swiss team develops low-temperature deposition for transparent perovskite

Perovskite PV continues to deliver encouraging results pointing to a future in which pervoskite-silicon or perovskite-thin film cells deliver conversion efficiencies significantly in excess of 20%. The Swiss Federal Laboratories for Materials Science and Technology (EMPA) is the latest to publish results in the this field, having developed a low-temperature process to produce semi-transparent perovskite cells.

The EMPA team employed a “hybrid thermal evaporation-spin coating technique” to produce a hysteresis-free perovskite PV cell, that can operate as a bifacial solar cell and in a tadem application due to its semi-transparent nature. An efficiency of 14.2% was achieved using the technique.

Through employing a “high-mobility hydrogenated indium oxide” rear electrode, the cell achieves 72% near-red light transmittance. The rear electrode is deposited using room-temperature radio-frequency magnetron sputtering.

By producing the perovskite device at low temperatures, less than 50C, the EMPA team notes that the process can be employed on plastic substrates for the production of flexible, semi-transparent cells.

The elimination of the J-V hysteresis effect, commonly exhibited by perovskite PV devices, allows for stable performance s and accurate conversion efficiency measurement.

The EMPA research produced a CIGS-pervoskite tandem device using its low-temperature technique, with the result being a 20.5% efficiency cell.

The findings were published in the journal Nature Communications earlier this month.

A great deal of hype has surrounded the market potential for flexible PV devices for some time, and the EMPA researchers note that there is still some way to go before its perovskite process could be commercialized.

“What we have achieved now is just the beginning,” EMPA’s Ayodhya Tiwori told optics.org. “We will have to overcome many obstacles before reaching this ambitious goal. To do this, we will need lots of interdisciplinary experience and a large number of combinatorial experiments until we have found a semi-transparent high-performance cell together with the right base cell, and technologies for electrical interconnections of these solar cells.”

With a large number of teams performing research on perovskite photovoltaics at present, significant progress is being made with the technology. Along with the EMPA team’s low-temperature process, increases in voltage, silicon heterojunction-pervoskite tandem cells and enhanced uniformity over larger substrates all point to a bright future for the technology.

Importantly, work on enhancing perovskite stability appears to be yielding results, with Dyesol claiming last month to have achieved less that 10% efficiency degradation with a perovskite cell when exposed to full sun intensity light for over 1,000 hours.

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