Researchers from the Korea Advanced Institute of Science and Technology (KAIST) and Sungkyunkwan University have developed a perovskite-based semi-transparent solar cell that is reportedly highly efficient and functions very effectively as a thermal mirror.
A major key to achieving semitransparent solar cells is to develop a transparent electrode for the cell's uppermost layer that is compatible with the photoactive material. The Korean team developed a 'top transparent electrode' (TTE) that works well with perovskite solar cells. The TTE is based on a multilayer stack consisting of a metal film sandwiched between a high refractive index layer and an interfacial buffer layer. This TTE, placed as a solar cell's top-most layer, can be prepared without damaging ingredients used in the development of perovskite solar cells. Unlike conventional transparent electrodes that only transmit visible light, the team's TTE both allows visible light to pass through and reflects infrared rays.
The semi-transparent solar cells made with the TTEs exhibited an average power conversion efficiency as high as 13.3%, reflecting 85.5% of incoming infrared light. The team stresses that currently available crystalline silicon solar cells have up to 25% efficiency but are opaque.
The team believes that if the semi-transparent perovskite solar cells are scaled up for practical applications, they can be used in solar windows for buildings and automobiles, which not only generate electrical energy but also allow smart heat management in indoor environments, thereby utilizing solar energy more efficiently and effectively.