A team of researchers from the National University of Singapore (NUS) has set a new record in the power conversion efficiency of solar cells made using perovskite and organic materials.
The team demonstrated a power conversion efficiency of 23.6% – this, according to the researchers, is the best performance for this type of solar cells to date. This achievement is a significant leap from the current power conversion rate of about 20% reported by other studies on perovskite/organic tandem solar cells.
Dr. Chen Wei, Research Fellow at the NUS Department of Chemical and Biomolecular Engineering, said the latest research is approaching the power conversion rate of 26.7% of silicon solar cells, which is dominating solar technology in the current PV market.
The tandem solar cell comprises two or more subcells electrically connected using interconnecting layers (ICLs) that play a critical role in determining the performance and reproducibility of a device. Although perovskite/organic tandem solar cells are attractive for next-generation thin-film photovoltaics, their efficiency lags behind other types of tandem solar cells.
To address this technological challenge, the NUS research team developed a novel and efficient ICL that reduces voltage, optical and electrical losses within the tandem solar cell. The ICL layer structure is based on a 4-nm-thick sputtered indium zinc oxide layer inserted between organic bathocuproine and molybdenum oxide with enhanced electrical properties and transmittance in the near-infrared region.
Through these improvements, researchers achieved a maximum efficiency of 23.6% in the perovskite/organic tandem solar cell. In addition, the tandem device retained 90% initial efficiency after 500 hours of maximum power point tracking under continuous illumination.
Assistant professor Hou Yi said their discovery opens the door to thin-film tandem solar cells that are flexible, light-weight, low cost, and ultra-thin, which could have wide-ranging applications such as in solar-powered blinds, vehicles, boats, and other mobile devices.
“Our study shows the great potential of perovskite-based tandem solar cells for future commercial application of photovoltaic technology. Building on our new discovery, we hope to further improve the performance of our tandem solar cells and scale up this technology,” said Asst Prof Hou.