Optimizing the Electron Transport Layer in Quantum Dot Solar Cells

The current climate crisis has sparked an increasing demand for accessible renewable energy sources. Solar energy has the potential to be a dominant energy source; however, current solar technologies are not ideal energy alternatives, primarily due to their high costs. Quantum dot solar cells (QDSCs) are thin film solar technologies that are light, flexible, and less expensive than prevailing solar technologies. QDSCs utilize the tunability of the band gap and electron affinity of the semiconductor quantum dots to optimize the energy output. The electron transport layer (ETL) permits the flow of electrons from the photoactive layer (PAL) to the front contact, but blocks transportation of holes from the PAL due to the energy band alignment of each semiconductor. The current standard ETL used in QDSCs is zinc oxide (ZnO) which has a conduction band edge with energy greater than that of the quantum dot PAL, PbS-I,Cl, used in the Van Ryswyk Lab. The energy band misalignment at the ETL-PAL interface is not favorable for electron movement and allows for charge recombination. Through solid state doping with cesium (Cs) and magnesium (Mg) of the ZnO ETL, the conduction band energy of the ETL is lowered. This project uses blade coating to deposit the CsMg-ZnO ETL on the cell which is scalable to industrial level manufacturing. By adopting scalable fabrication methods while optimizing the ETL through solid state doping, this project improves PbS-based QDSCs such that they can be an affordable and effective alternative energy technology.