Researchers in Thailand built an indoor perovskite solar cell with a low-cost carbon electrode architecture. The fabrication process is based on antisolvent coating and vacuum thermal annealing (VTA) and is said to result in better perovskite film quality.
“VTA leads to a compact, dense and hard morphology while suppressing the trap states at surfaces and grain boundaries that are key to exciton loss,” they noted, emphasizing the importance of the second step to produce a high-quality perovskite layer. “Since the intensity of indoor light is at least 300 times lower than that of sunlight, the dense and homogeneous perovskite formation induced by vacuum thermal annealing is valuable.”
The researchers carried out the process through a vacuum bottle connected to a vacuum pump with adjustable pressure and located on top of a hot plate to regulate the temperature. They used a perovskite material known as FA0.45Mon0.49Cs0.06Pb(I0.62Bro0.32Cl0.06)3 treated with bromide and chloride. After treatment, its energy band was 1.80 eV.
They built the cell from a substrate made of fluorine-doped tin oxide (FTO), an electron transport layer (ETL) based on tin(IV) oxide (SnO2), a perovskite absorber, a hole transport layer (HTL) made of Spiro. -OMeTAD, carbon electrode and second FTO layer. The active surface area of the device is 0.04 cm2.
Tested in indoor light 1000 lux, cell power conversion efficiency was 27.7%, open voltage 0.93 V and short circuit current 0.16 mA/cm2, with a peak power of up to 32.0%. The reference device without VTA treatment achieved 25.5% efficiency, 0.91 V breakdown voltage and 0.16 mA/cm short-circuit current.2with a peak power of 30.7%.
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“VTA leads to reduced surface roughness and electronic traps in both bulk and surface,” the team said, citing the superior performance of the VTA-based cell. “VTA opens doors for robust perovskite formation and can be practically adapted to different perovskite compositions towards desired optoelectronic applications in modern society.”
The solar cell is presented in the study “Sense perovskite formation via vacuum thermal annealing using indoor perovskite solar cells”, which was published Scientific reports.