Researchers at the Indian Institute of Technology Bombay have reported NIR-transparent perovskite solar cells (PSCs) with the stable triple cation perovskite as the photo-absorber and subsequent integration with a Si solar cell in a 4T tandem device. The scientists said that the cell provides outstanding stability in the dark, as well as continuous heating conditions.
The top perovskite cell incorporates a room-temperature sputtered transparent conducting electrode (TCE) as a rear electrode. It has an n–i–p structure and utilizes an anti-reflecting coating, an electron transport layer (ETL) made of tin(IV) oxide (SnO2), a perovskite layer, a molybdenum oxide (MoOx) layer, and a spiro-OMeTAD hole transport layer (HTL). The MoOx buffer layer protects the perovskite photo-absorber and charge transport layers from any sputter damage.
The team's recent study details the complete device architecture, explains the fabrication process and provides the raw data related to dark and light I-V scan and EQE spectrum, as part of a general approach that aims to share information to promote their fellow academics and the general industry.
“The ambipolar property of the perovskite photo-absorber material and suitable band alignment with the ETL and HTL enables efficient charge transport toward the appropriate carrier selective contacts; hole transport to the HTL and electron transport to the ETL,” explained the scientists.
This top cell technology has a power conversion efficiency of 16% in a large-area device, measuring 0.805 cm2, and 17.1% in a small–area device measuring 0.175 cm2. The cell was combined with a 23.0%-efficient monocrystalline PERC cell in a 4T silicon-perovskite tandem device and reached an overall efficiency of 26.03%.
“This was made possible through careful optimization of the TCE, busbar, perovskite photo absorber layer thickness, and implementation of ARC on both sides,” the team explained, adding that the 4T tandem cell might be used as a replacement for glass panels of buildings or for building-integrated photovoltaics (BIPV).