Encapsulation of Perovskite Solar Cells with Transparent Conductive Composites for Long-Term Stability
| dc.contributor.advisor | Gaillard, Nicolas | |
| dc.contributor.author | Xu, Jackson | |
| dc.contributor.department | Mechanical Engineering | |
| dc.date.accessioned | 2024-07-02T23:41:58Z | |
| dc.date.available | 2024-07-02T23:41:58Z | |
| dc.date.issued | 2024 | |
| dc.description.degree | M.S. | |
| dc.identifier.uri | https://hdl.handle.net/10125/108351 | |
| dc.subject | Mechanical engineering | |
| dc.subject | conductive | |
| dc.subject | degradation | |
| dc.subject | perovskite | |
| dc.subject | solar | |
| dc.subject | stability | |
| dc.subject | transparent | |
| dc.title | Encapsulation of Perovskite Solar Cells with Transparent Conductive Composites for Long-Term Stability | |
| dc.type | Thesis | |
| dcterms.abstract | Perovskite solar cells (PSC) are one of the most promising emerging technologies in photovoltaics (PV). Since its inception in 2009 with an initial power conversion efficiency (PCE) of 3.9%, studies have demonstrated a PCE as high as 26.1% for single-junction PSCs. This is not only the most rapid improvement of any PV technology to date, but also a competitive candidate in terms of PCE to other veteran solar cells, including silicon. In addition, PSCs are inexpensive to produce, highly scalable as a result of solution processing, and has a wide range of applications due to its favorable material characteristics such as tunable bandgap, lightweight quality, and mechanical flexibility. However, perovskites rapidly degrade under relevant operating conditions including exposure to water vapor and oxygen gas in the atmosphere, intense visible and ultraviolet (UV) illumination, and high temperatures that have limited its commercial success. So far, the best performing unencapsulated PSCs are able to operate in atmospheric conditions for approximately 1,000 hours before dropping to 80% of their initial PCE and are nowhere near the standard lifespan of mature PV technologies on the market ranging from 20-25 years. While glass-glass encapsulation is common practice for solar cells, it significantly increases module weight and is inflexible which restricts solar cell architectures and operational modes. As such, the focus of this thesis is to improve upon traditional encapsulation schemes via a transparent and conductive composite (TCC) gas diffusion barrier comprised of conductive 50 m diameter spheres embedded in a polymer matrix. This research builds upon previous studies at HNEI that have investigated similar methods to fabricate transparent conductive adhesives for bonding layers in multi-junction solar cell devices but aims to specifically address application with single-junction PSCs as a protective barrier for long-term stability. To validate the durability of the TCC system, free-standing samples were exposed to an outdoor environment at the University of Hawai‘i at Mānoa (tropical semi-arid climate) for a total of 1,000 hours. During this testing period, the samples aged in real-world operating conditions with a total solar insolation of 119.2 kWh/m2 (daily average: 5.96 kWh/m2), cumulative precipitation of 64.5 mm (daily average: 3.11 mm), average daily temperature of 24.52 °C, and average relative humidity of 74.1%. Out of plane conductivity and optical transparency were intermittently measured throughout the experiment to benchmark its optoelectronic performance. The results demonstrate that after 1000 hours of outdoor exposure, the TCC samples retain over 95% of initial optical transmission in the 370 nm - 2000 nm wavelength region and maintained a series resistance below 0.1 cm2 throughout. These results demonstrate that the TCC can maintain high optical transparency and high conductivity (low resistance) to minimally impact the PSC functionality when deployed as a protective barrier by facilitating sunlight absorption and electrical current collection. Furthermore, the water vapor transmission rate (WVTR) of the TCC and the corresponding polymer system (i.e., without conductive microspheres) were measured to quantify the encapsulant gas diffusion properties. Both the TCC and polymer system measure WVTR greater than 1·10-1 g/m2/day, which is consistent with typical polymer systems. Although this is significantly higher than the minimum WVTR of 1·10-3 g/m2/day to act as a sufficient gas-barrier for long-term stability, these measurements will facilitate future developments in multilayer TCC architectures, which is a promising approach to further reduce WVTR. To benchmark compatibility and durability, Cs0.5FA0.8MA0.15Pb2.55Br0.45 PSC samples were coated with the TCC system for testing. The PV performance measured both as synthesized after TCC encapsulation showed near coincident solid-state performances which confirmed compatibility and negligible impact to PSC performance. Furthermore, TCC-coated PSCs were able to preserve over 90% of their initial PCE after 1,000 hours of accelerated durability testing (quasi-maximum power point light soaking at 55C in ambient air) while uncoated samples degraded to less than 25% of their initial PCE within 300 hours. Therefore, optimization of this novel encapsulation scheme will serve to protect PSCs to address the long-term stability problems while improving upon traditional encapsulation methods in terms of weight, flexibility, conductivity, and operational modes. | |
| dcterms.extent | 109 pages | |
| dcterms.language | en | |
| dcterms.publisher | University of Hawai'i at Manoa | |
| dcterms.rights | All UHM dissertations and theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission from the copyright owner. | |
| dcterms.type | Text | |
| local.identifier.alturi | http://dissertations.umi.com/hawii:12167 |
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