The additive consists of a molecule known as 4-guanidinobenzoic acid hydrochloride (GBAC), a raw material and intermediate commonly used in organic synthesis, pharmaceuticals, agricultural chemicals, and dyes. The structure of the solar cell is ap–i–n, and thanks to the new additive, it showed a greatly reduced defect density in the perovskite film, which in turn leads to a reduction in non-radiative recombinations.
The additive, which they described as “multifunctional and non-volatile,” consists of a molecule known as 4-guanidinobenzoic acid hydrochloride (GBAC), which is a raw material and intermediate commonly used in organic synthesis, pharmaceuticals, agricultural chemicals, and dyes.
“This molecule can also act as an effective defect passivation linker in an annealed perovskite film due to its non-volatility, leading to significantly reduced non-radiative recombination loss and improved film quality,” the researchers explained, noting that its addition creates a hydrogen-bonded interphase and allows for high-quality perovskite films.
The device has an ap–i–n structure and showed a greatly reduced defect density in the perovskite film, which in turn​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​a, leads to reduced non-radiative recombinations.
The cell achieved a maximum efficiency of 24.8% and a certified efficiency of 24.5%, and the result was confirmed by Japan Electrical Safety & Environment Technology Laboratories (JET). “The total energy dissipation of the device was reduced to 0.36 eV, which is one of the lowest energy dissipation among perovskite photovoltaic devices with high power conversion efficiency,” the researchers added.
The cell was also able to maintain 98% of its original efficiency for over 1000 hours under continuous heating at approximately 65 C in a nitrogen-filled glovebox.
The scientists also built a larger 1 cm2 area device using this cell technology, and the new cell achieved an efficiency of 22.7 percent, which they say shows the technology is fully scalable. “This efficient approach can also be applied to broadband perovskites and wide-area devices for reduced voltage drop and high efficiency,” they said.
They published their findings in “A water-bridged intermediate for perovskite solar cells with improved efficiency and stability,” published in natural photonics.
