Indoor perovskite solar cell built with triple passivation strategy achieves 37.6% efficiency

An international research team has constructed an indoor perovksite PV device by using a triple passivation treatment to reduce crystal defects in the perovskite film. The cell achieved remarkable efficiency and was also able to retain 92% of its initial performance after 3,200 h.

A group of researchers led by University College London has fabricated a perovskite indoor solar cell that is claimed to be six times more efficient than the best commercially available indoor solar cells.

Conceived for applications in keyboards, remote controls, alarms and sensors, the device was manufactured with what the scientists described as triple passivation treatments (TPT) aimed at reducing crystal defects in the perovskite film.

“The solar cell with these tiny defects is like a cake cut into pieces,” said lead author Siming Huang. “Through a combination of strategies, we have put this cake back together again, allowing the charge to pass through it more easily. The three ingredients we added had a synergistic effect, producing a combined effect greater than the sum of the parts.”

The triple strategy consisted of using three different chemicals, namely rubidium chloride (RbCl), N,N-dimethyloctylammonium iodide (DMOAI) and phenethylammonium chloride (PEACl), to enable the growth of perovskite crystals with minimal strains.

“The addition of RbCl promotes uniform crystal growth, alleviates local lattice strain, and passivates energy barriers near the perovskite-contact interface, while DMOAI and PEACl effectively suppress bulk and surface defects, as well as photo-induced halide phase segregation,” the scientists explained, noting that DMOAI and PEACI were added to stabilize iodide and bromide ions, preventing them from migrating apart and bunching into different phases, which disrupts the flow of charge through the material.

For the cell absorber, they used a perovskite material known as FA_0.64MA_0.36Pb(I_0.64Br_0.36)₃, with an energy bandgap of 1.75 eV.

The researchers employed X-ray diffraction (XRD) to evaluate the impact of the proposed triple passivation strategy on the crystal structure and quality of perovskite films. “Compared to the control films, the DMOAI-only passivated films exhibited 2.7 times higher PL intensity, while that of the target films increased by 3.6 times, demonstrating that TPT effectively passivates defects,” they emphasized.

Tested under standard indoor illumination conditions, the solar cell achieved a power conversion efficiency of 37.6%. It was also found to retain 92% of its initial efficiency after being stored for 3,200 h at room temperature and 5–10% relative humidity, compared to a control perovskite device built without TPT that retained only 76% of its initial performance.

“In a harsh test of 300 hours of continuous intense light at 55 C, the new solar cells retained 76% of their performance, while the control device dropped to 47%,” the research team further explained.

The details of the PV device can be found in the study “Enhancing Indoor Photovoltaic Efficiency to 37.6% Through Triple Passivation Reassembly and n-Type to p-Type Modulation in Wide Bandgap Perovskites,” published in Advanced Functional Materials. The research team included academics from China's Ordos New Energy Research Institute, Imperial College London, London South Bank University, Switzerland's Ecole Polytechnique Fédérale de Lausanne (EPFL), and Chinese startup Phoenixolar Co. Ltd. 

“Our TPT reassembly strategy is a powerful approach to simultaneously suppress non-radiative recombination, minimize halide phase segregation, and enhance both the efficiency and long-term stability of wide bandgap perovskite solar cells for i-PV applications,” they concluded.