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Creators/Authors contains: "Afshari, Hadi"

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  1. ; ; ; ; ; ; ; ; ; ; et al (, Journal of Physics: Energy)
    Irvine, John (Ed.)
    Abstract Here, the radiation hardness of metal halide perovskite solar cells exposed to space conditions versus the effects of environmental degradation are assessed. The relative response of the constituent layers of the architecture to radiation is analyzed, revealing a general resilience of the structure when assessed across varying proton energy levels and fluences. However, despite the tolerance of the structure to irradiation, sensitivity to environmental degradation is observed during the transit of the device between the radiation and characterization facilities. Experimental evidence suggests the NiOx/perovskite interface is particularly sensitive to the effects of humidity and/or temperature exposure, while the irradiation of the devices appears to induce thermally activated annealing: improving the solar cells upon radiation exposure. 
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  2. ; ; ; ; ; ; ; ; ; (, Solar RRL)
    ACIGS solar cells are exposed to targeted radiation to probe the front and back interfaces of the absorber to assess the impact of space environments on these systems. These data suggest ACIGS cells are more radiation‐hard than early CIGS devices likely due to the lower defect densities and more ideal interfaces in the ACIGS system. A combination ofJ–Vand external quantum efficiency measurements indicates some improvement in the performance of the device due to the effects of local heating in the dominant ionizing electronic energy loss regime of proton irradiation that anneal the upper CdS/ACIGS interface. However, nonionizing energy losses at the base of the solar cell also appear to inhibit minority carrier collection from the back of the cell at the ACIGS/Mo interface, which is discussed in terms of defect‐mediated changes in the doping profile, the Ga/Ga+In ratio, and impurity composition after proton irradiation. 
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  3. ; ; ; ; ; ; ; ; (, APL Energy)
    The high tolerance and stability of triple halide perovskite solar cells is demonstrated in practical space conditions at high irradiation levels. The solar cells were irradiated for a range of proton energies (75 keV, 300 keV, and 1 MeV) and fluences (up to 4 × 1014 p/cm2). The fluences of the energy proton irradiations were varied to induce the same amount of vacancies in the absorber layer due to non-ionizing nuclear energy loss (predominant at <300 keV) and electron ionization loss (predominant at >300 keV). While proton irradiation of the solar cells initially resulted in degradation of the photovoltaic parameters, self-healing was observed after two months where the performance of the devices was shown to return to their pristine operation levels. Their ability to recover upon radiation exposure supports the practical potential of perovskite solar cells for next-generation space missions. 
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  4. ; ; ; ; ; ; ; ; ; (, ACS Energy Letters)
    Prashant V. Kamat (Ed.)
    Formamidinium cesium (FACs) perovskites solar cells have been shown to be among the most stable metal halide perovskites. Here, high-temperature data are presented which systematically and statistically demonstrate the high thermal operation of this system to temperatures in excess of 200 °C. Device measurements between 250 K and 490 K show that while some loss of performance is evident at higher temperature, this is driven by reversible halide segregation with no evidence of a structural phase transition over the measurement range probed. Moreover, upon reduction of the temperature back to ambient the power conversion efficiency is retained. 
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  5. ; ; ; ; ; ; ; ; ; (, ACS Applied Materials & Interfaces)
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