en.Wedoany.com Reported - A research team composed of scientists from Korea University, the University of Toledo, and Seoul National University has constructed a three-dimensional perovskite solar cell that achieved an efficiency of over 26% and an operational lifespan exceeding 24,000 hours under laboratory testing conditions. The research utilized halide perovskites, a material that has been difficult to manufacture in the past.
As silicon-based solar cells reach their maximum energy conversion potential, scientists are turning their attention to perovskites, a material that can not only achieve higher efficiency solar cells but also make them more economical. Professor Jun Hong Noh of Korea University has been investigating a solar cell concept where charge transport layers are placed on both sides of the absorber layer to passivate surfaces and interfaces. This method has been used in silicon heterojunction (HIT) solar cells, but Noh's idea used halide perovskites, which are more challenging to fabricate.
To overcome the structural challenges, Noh and his colleagues turned to two-dimensional (2D) halide perovskites with a wide bandgap. By bringing 2D films into contact with 3D films and applying heat and pressure, the researchers grew a crystalline 2D layer on the 3D surface. The team discovered that merely bringing the 2D and 3D materials into contact altered the optical properties of the 3D layer, including its photoluminescence, even without heat or pressure. "Interestingly, these changes were reversible and strongly dependent on the organic cations," Noh said in a press release. "We were really excited when we further discovered that this contact interaction significantly affects phase transitions in 3D perovskites and originates from the interactions between organic cations in the 2D and 3D layers."
The researchers hypothesized that thermal treatment of the two films already in contact with each other could lead to structural evolution of the 3D layer. To verify this hypothesis, the team applied it to FAPbI₃ perovskite films, which typically suffer from imperfect crystallization. The hypothesis proved correct when the film's lattice parameters were very close to the theoretical values calculated by the team. Even the FAPbI₃ film powder fabricated by the research team maintained a more stable phase than FAPbI₃ produced through conventional methods. "Efficiency losses stem from trap states on surfaces and within the bulk phase, which are directly related to defects. Similarly, phase transitions are known to initiate from defects. Therefore, achieving a near-perfect crystal structure is one of the most critical challenges in this field," Noh added.
The researchers integrated their perovskite films into conventional solar cells and found the efficiency boosted to 26.25%, demonstrating an operational lifespan of 24,000 hours in accelerated testing. This 2D/3D film contact process is highly scalable and can be used to fabricate larger-area films with fewer defects. The team is currently working on applying this method to all-perovskite tandem solar cells, where low-bandgap perovskites need to be deposited on top of wide-bandgap layers at low temperatures. The research findings were published in Nature Energy.
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