Perovskite Solar Cells for Space Applications
Abstract
Perovskite solar cells (PSC) technology has seen significant advancements since its initial introduction in 2009. There is a growing interest in utilizing PSC technology for space application. However, the stability of PSCs in space environments remains unclear. This thesis aims to investigate the degradation mechanism of perovskite in space conditions and improve the performance and stability of PSCs to meet the requirements for space missions.
PSC technology offers a promissing power option for space applications due to its high power-to-weight ratio and tolerance to space radiation. A new simulation-based method has been developed to predict the degradation of PSCs under proton radiation. This method uses ion scattering simulations to generate depth-dependent defect profiles based on proton energy and fluence, which are then used in optoelectronic simulations to predict degradation. The study compares the radiation tolerance of inorganic perovskite CsPbI2Br and organic-inorganic perovskite FAMAPbI3, and predicts that CsPbI2Br and FAMAPbI3 cells retain 62% and 65% of their initial efficiencies after 100 keV proton radiation with a dose of 1e14 p.cm-2, respectively. It also shows that radiation direction must be considered when predicting rdiation tolerance, as the spatial overlap between photogenerated carriers and radiation-induced defects significantly impacts the cell performance. This method is used to predict mission end-of-life performance of PSCs, taking into account the full proton radiation energy spectrum and fluence and the incident direction.
Additionally, the study assesses the impact of 10 MeV proton radiation on perovskite films and PSCs at fluences in range from 1e12 to 1e14 p.cm-2, which is equivalent to 1 to 100 years in Geosynchronous equatorial orbit (GEO) without any shielding or cover. For the first time, void formation and material ablation were detected, showing the degradation mechanism due to structural damage. As a result, these led to the degradation of PSCs to 89% of the initial performance at the highest dose.
Finally, the study disscusses the device performance and stability improvements via management of excess lead iodide (PbI2) in PSCs. This method, known as buried interface modification, effectively adjusts the amount of excess PbI2 in PSCs at both the bottom surface and the bulk of the perovkite layer, achieving high efficiencies with negligible hysteresis and excellent stability via defect passivation. The approach is effective for both negative-intrinsic-possitive (n-i-n) and possitive-intrinsic-negative (p-i-n) structures.