Researchers report triple junction perovskite solar cell with 24.3% efficiency

• Researchers from the University of Toronto in Canada, Northwestern University, The University of Toledo and University of North Carolina at Chapel Hill in the United States, King Abdullah University of Science and Technology (KAUST) in Saudi Arabia, Yunnan University in China, Ecole Polytechnique Fedérale de Lausanne (EPFL) in Switzerland and also University of Warwick in the UK have developed a triple-junction perovskite solar cell with a document performance of 24.3% with an open-circuity voltage of 3.21 V.

The NREL has certified the cell's quasi-steady-state efficiency as 23.3%, which the team mentioned is the initially reported licensed effectiveness for perovskite-based triple-junction solar cells. They included that triple-junction perovskite solar cells have until now showed a maximum efficiency of around 20%.

In their current work, the group begun by using a perovskite which was made from a mix of various compounds, consisting of cesium, lead, tin, iodine, bromine, as well as small organic molecules. Its top layer is composed of combined halide perovskites with a specifically high percentage of bromine (Br) as well as iodine (I).

" What occurs in light-induced phase separation of these combined perovskites is that the bombardment of high-frequency photons creates the phases that are richer in bromine to get divided from those that are abundant in iodine," claimed Dr. Hao Chen, co-lead author of the research study. "This causes an increase in defects and also a decline in general efficiency."

To overcome this challenge, the scientists used solid-state magnetic vibration spectroscopy to simulate the result of altering the structure of the crystals. They located that changing the organic molecules for an all-inorganic perovskite structure and also replacing cesium (Cs) with the element rubidium (Rb) subdued light-induced phase separation (LIPS).

" We locate that Rb, with a smaller sized cation radius than Cs, can be doped into the inorganic perovskite lattice and that the upper limit of Rb doping content is favorably correlated with Br content," the team stated. "The around 2.0 eV [band gap] Rb/Cs mixed-cation inorganic perovskites with a larger degree of lattice distortion than their Cs-based equivalents show reduced LIPS as a result of the decreased average interatomic range of the [Cs or Rb] -site cation and also I, and the boosted energy barrier of halide ion migration."

The triple-junction cells supposedly maintained 80% of their initial performance complying with 420 hrs of operation at the maximum power point.