Perovskite photovoltaic devices are one of the most promising thin-film photovoltaic technologies, as they conjugate high performance, low material costs, flexibility and color tunability. These characteristics can be applied in innovative applications for the collection of solar power, as well as in the improvement of the performance of current photovoltaic technologies through integration in tandems. Moreover, the up-scaling of this technology is happening quickly, with reports of area and efficiencies of modules constantly increasing.
The hardest challenge left for this technology to become commercially available is the guarantee of long-term stability. This doctoral research project is an in-depth investigation of the degradation mechanisms occurring in archetypal n-i-p perovskite photovoltaic devices. The understanding developed in this work identifies the weakest points of the technology and suggests how new materials and designs can enhance its long-term stability.
More specifically, we investigate the key degradation mechanisms triggered by stress factors encountered by photovoltaic devices in the field: atmospheric gases, elevated temperatures and light. The investigation of how the atmospheric gases influence the device, reveals that oxygen and water vapor only cause irreversible degradation in the presence of light.
However, we demonstrate that device degradation can be mitigated by cost-effective carbon nanotube contacts. Next, we systematically investigate and quantify the kinetics of the degradation mechanisms occurring at elevated temperatures.
The quantification of the kinetics allows for the development of the first model to estimate the lifetime of perovskite photovoltaic devices based on weather data. After, we demonstrate that the key degradation mechanism occurring during continuous illumination is triggered by an additive utilized to improve the performance of the devices. Finally, we provide more general conclusions and an outlook on how to further improve the stability of perovskite photovoltaic and its investigation.
Bastos, J., 2019. Degradation Mechanisms in Perovskite Photovoltaic Devices.