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- Creators: Byrne, Jared
- Creators: Bowden, Stuart
Despite the promising potential of GaP/Si heterojunction solar cells, there are two main obstacles to realize high performance photovoltaic devices from this structure. First, the growth of the polar material (GaP) on the non-polar material (Si) is a challenge in how to suppress the formation of structural defects, such as anti-phase domains (APD). Further, it is widely observed that the minority-carrier lifetime of the Si substrates is significantly decreased during epitaxially growth of GaP on Si.
In this dissertation, two different GaP growth methods were compared and analyzed, including migration-enhanced epitaxy (MEE) and traditional molecular beam epitaxy (MBE). High quality GaP can be realized on precisely oriented (001) Si substrates by MBE growth, and the investigation of structural defect creation in the GaP/Si epitaxial structures was conducted using high resolution X-ray diffraction (HRXRD) and high resolution transmission electron microscopy (HRTEM).
The mechanisms responsible for lifetime degradation were further investigated, and it was found that external fast diffusors are the origin for the degradation. Two practical approaches including the use of both a SiNx diffusion barrier layer and P-diffused layers, to suppress the Si minority-carrier lifetime degradation during GaP epitaxial growth on Si by MBE were proposed. To achieve high performance of GaP/Si solar cells, different GaP/Si structures were designed, fabricated and compared, including GaP as a hetero-emitter, GaP as a heterojunction on the rear side, inserting passivation membrane layers at the GaP/Si interface, and GaP/wet-oxide functioning as a passivation contact. A designed of a-Si free carrier-selective contact MoOx/Si/GaP solar cells demonstrated 14.1% power conversion efficiency.
Sun Stop Solar, is a solar module development and manufacturing company that utilizes a unique class of materials, perovskites, as the solar cells’ absorption layer. Perovskites are a unique class of compounds with some perovskites being able to absorb photons and excite electrons to create current. Sun Stop Solar plans to initially begin by developing the foundational technological patent for our perovskite-based single-junction solar cells. Sun Stop Solar plans to initially begin by first having a patent set up, then licensing our patent to a manufacturer, and slowly building towards manufacturing our own solar modules.
Sun Stop Solar, is a solar module development and manufacturing company that utilizes a unique class of materials, perovskites, as the solar cells’ absorption layer. Perovskites are a unique class of compounds with some perovskites being able to absorb photons and excite electrons to create current. Sun Stop Solar will focus on first developing the patent, licensing the technology to a manufacturer, and slowly garnering funds to launch our own manufacturing eventually. Sun Stop Solar is offering a domestic, affordable, and sustainable solution for the current solar market.
Sun Stop Solar, is a solar module development and manufacturing company that utilizes a unique class of materials, perovskites, as the solar cells’ absorption layer. Perovskites are a unique class of compounds with some perovskites being able to absorb photons and excite electrons to create current. Sun Stop Solar will focus on first developing the patent, licensing the technology to a manufacturer, and slowly garnering funds to launch our own manufacturing eventually. Sun Stop Solar is offering a domestic, affordable, and sustainable solution for the current solar market.
Prior literature on Cu-contact reliability tended to focus on accelerated testing at the cell and wafer level that may not be entirely replicative of real-world environmental stresses in PV modules. This thesis is aimed at advancing the understanding of Cu-contact reliability from the perspective of quasi-commercial modules under more realistic stresses. In this thesis, c-Si solar cells with Cu-plated contacts are fabricated, made into PV modules, and subjected to environmental stress in an attempt to induce hypothesized failure modes and understand any new vulnerabilities that Cu contacts might introduce. In particular, damp heat stress is applied to conventional, p-type c-Si modules and high efficiency, n-type c-Si heterojunction modules. I present evidence of Cu-induced diode degradation that also depends on PV module materials, as well as degradation unrelated to Cu, and in either case suggest engineering solutions to the observed degradation. In a forensic search for degradation mechanisms, I present novel evidence of Cu outdiffusion from contact layers and encapsulant-driven contact corrosion as potential key factors. Finally, outdoor exposures to light uncover peculiarities in Cu-plated samples, but do not point to especially serious vulnerabilities.