Researchers at the Pennsylvania State University, King Abdullah University of Science & Technology (KAUST) and University of Toronto (U of T) have devised a colloidal-quantum-dot solar cell with a record conversion efficiency using atomic-ligand passivation.
The researchers have presented their paper titled, ‘Colloidal-quantum-dot photovoltaics using atomic-ligand passivation,’ in the journal Nature Materials. Quantum dots, which are semiconductors at the nanoscale, capture light and transform it into a source of energy. Their nanoscale allows their coating over flexible surfaces such as plastics. This allows the production of cheaper solar cells with better durability compared to silicon-based solar cells.
In the paper, the researchers have demonstrated how they have shrunk the sheaths that cover the quantum dots to atomic thick layers. If the gap between the quantum dots is low, higher the solar cell efficiency. Hence, the optimal design should closely pack the quantum dots in concert. To achieve this, the researchers have utilized inorganic ligands that bind the quantum dots tightly, while utilizing minimal space.
Dr. Jiang Tang, a member of the research team, commented that the researchers sheathed each particle by a single layer of atoms, causing the quantum dots to be packed as a highly dense solid. The researchers demonstrated the optimal electrical currents and the optimal overall power conversion efficiency that were unprecedented in colloidal-quatum-dots solar cells. A Newport-based external laboratory under the accreditation of the US National Renewable Energy Laboratory certified the performance results.
John Asbury, a member of the research team, stated that the research team demonstrated that it can eliminate charge traps where electrons get trapped, while tightly packing the quantum dots together. The combination of tight packing and elimination of charge traps allowed electrons to transport quickly and smoothly via the solar cells, resulting in record conversion efficiency.
Professor Dmitri Talapin of The University of Chicago stated that this discovery demonstrates the significance of inorganic ligands in devising practical devices. This novel surface chemistry paves the way for the development of stable and efficient quantum dot solar cells and also has an impact on colloidal nanocrystal-based electronic and optoelectronic devices, he said.
Professor Aram Amassian of KAUST stated that the research team demonstrated that inorganic passivants were closely connected with the position of the quantum dots and it was a novel method to chemical passivation instead of nanocrystal ordering, causing the record-breaking performance of the colloidal quantum dot solar cell.
Source: http://www.utoronto.ca