The Resource Demand of Terawatt-Scale Perovskite Tandem Photovoltaics

Photovoltaics (PV) is the most important energy conversion technology for cost-efficient climate change mitigation. To reach the international climate goals, the annual PV module production capacity must be expanded to multi-terawatt scale. Economic and resource constraints demand the implementation cost-efficient multi-junction technologies, for which perovskite-based tandem technologies are highly promising. In this work, the resource demand of the emerging perovskite PV technology is investigated, considering two factors of supply criticality, namely mining capacity for minerals, as well as production capacity for synthetic materials. Overall, the expansion of perovskite PV to a multi-terawatt scale may not be limited by material supply if certain materials, especially cesium and indium, can be replaced. Moreover, organic charge transport materials face unresolved scalability challenges. This study demonstrates that, besides the improvement of efficiency and stability, perovskite PV research needs also to be guided by sustainable materials choices and design-for-recycling considerations

Experimental validation of a modeling framework for upconversion enhancement in 1D-photonic crystals

Photonic structures can be designed to tailor luminescence properties of materials, which becomes particularly interesting for non-linear phenomena, such as photon upconversion. However, there is no adequate theoretical framework to optimize photonic structure designs for upconversion enhancement. Here, we present a comprehensive theoretical model describing photonic effects on upconversion and confirm the model’s predictions by experimental realization of 1D-photonic upconverter devices with large statistics and parameter scans. The measured upconversion photoluminescence enhancement reaches 82 ± 24% of the simulated enhancement, in the mean of 2480 separate measurements, scanning the irradiance and the excitation wavelength on 40 different sample designs. Additionally, the trends expected from the modeled interaction of photonic energy density enhancement, local density of optical states and internal upconversion dynamics, are clearly validated in all experimentally performed parameter scans. Our simulation tool now opens the possibility of precisely designing photonic structure designs for various upconverting materials and applications

Upconversion solar cell measurements under real sunlight

The main losses in solar cells result from the incomplete utilization of the solar spectrum. Via the addition of an upconverting layer to the rear side of a solar cell, the otherwise-unused sub-bandgap photons can be utilized. In this paper, we demonstrate an efficiency enhancement of a silicon solar cell under real sunlight due to upconversion of sub-bandgap photons. Sunlight was concentrated geometrically with a lens with a factor of up to 50 suns onto upconverter silicon solar cell devices. The upconverter solar cell devices (UCSCDs) were also measured indoors using a solar simulator. To correct for differences in the spectral distribution between real sunlight and the solar simulator a spectral mismatch correction is required and is especially important to properly predict the performance when a non-linear response (e.g. upconversion) is involved. By applying a spectral mismatch correction, good agreement between the solar simulator measurements and the outdoor measurements using real sunlight was achieved. The method was tested on two different upconverter powders, β-NaYF4: 25% Er3+ and Gd2O2S: 10% Er3+, which were both embedded in a polymer. We determined additional photocurrents due to upconversion of 9.4 mA/cm2 with β-NaYF4 and 8.2 mA/cm2 with Gd2O2S under 94-suns concentration. Our results show i) the applicability of measurements using standard solar cell characterization equipment for predicting the performance of non-linear solar devices, and ii) underline the importance of applying proper mismatch corrections for accurate prediction of the performance of such non-linear devices

Vapor phase deposition of perovskite photovoltaics:Short track to commercialization?

While perovskite-based photovoltaics (PV) is progressing toward commercialization, it remains an open question which fabrication technology - solution-based, vapor-based, or combinations - will pave the way to faster economic breakthrough. The vast majority of research studies make use of solution-processed perovskite thin films, which benefit from a rapid optimization feedback and inexpensive to procure tools in modern research laboratories, but vapor phase deposition processes dominate today's established thin-film manufacturing. As research and development of vapor phase processed perovskite thin films are still strongly underrepresented in literature, their full potential is yet to be identified. In this collaborative perspective of academic influenced by industrial views, we convey a balanced viewpoint on the prospects of vapor-based processing of perovskite PV at an industrial scale. Our perspective highlights the conceptual advantages of vapor phase deposition, discusses the most crucial process parameters in a technology assessment, contains an overview about relevant global industry clusters, and provides an outlook on the commercialization perspectives of the perovskite technology in general.</p

Stau Search in IceCube

The tau lepton’s supersymmetric partner, the stau, appears in some models as the next-to-lightest supersymmetric particle. Their deacy process into the lightest superpartner is usually suppressed by supersymmetry breaking, which makes it a long-lived particle. In this scenario, its signature is a long, minimally ionizing track when traveling through the IceCube detector. Independent of their primary energy, the stau tracks appear like low-energy muons in the detector. A potential signal of staus would thus be an excess over muon tracks induced by atmospheric muon neutrinos. Our analysis focuses on the region around the horizon as here the ratio between stau signal and atmospheric background is largest. We will present the first sensitivity to constrain the stau mass using IceCube and demonstrate the potential of this analysis with future improvements