Philippe Holzhey

Abstract:

In the past few years, we have witnessed a rapid evolution of perovskite solar cells. In this study, we employ life cycle assessment (LCA) to identify the potential environmental impacts of perovskite solar cells (PSC) optimised for aerospace applications but could be used in conventional terrestrial applications too. One PSC module is manufactured by spin coating equipped with ITO glass and gold cathode. The other PSC module is manufactured by slot-die coating with a PET layer and carbon cathode and gold cathode respectively. Life cycle assessment is employed to compare potential environmental impact of two manufacture methods by impact method of Recipe(H), as well as the fabrication cost of PSC module. The primary data of material and energy used for fabricating PSCs are collected from spin coating with lab scale and slot-die coating with pilot scale. The life cycle impact assessment of the PSC module in the pilot scale shows much lower in all the assessed 18 impact categories than in the lab scale thanks to the material use efficiency and reducing energy consumption. Gold as a conduct electrode has the highest impacts in both spin coating and slot-die coating modules. Calculating with a two-year lifetime (typical of aerospace applications), the impact of global warming potential from the PSC module with carbon electrode with pilot scale used in a terrestrial application is calculated to be 12 g/kWh

Abstract:

Achieving the long-term stability of perovskite solar cells is arguably the most important challenge required to enable widespread commercialization. Understanding the perovskite crystallization process and its direct impact on device stability is critical to achieving this goal. The commonly employed dimethyl-formamide/dimethyl-sulfoxide solvent preparation method results in a poor crystal quality and microstructure of the polycrystalline perovskite films. In this work, we introduce a high-temperature dimethyl-sulfoxide-free processing method that utilizes dimethylammonium chloride as an additive to control the perovskite intermediate precursor phases. By controlling the crystallization sequence, we tune the grain size, texturing, orientation (corner-up versus face-up) and crystallinity of the formamidinium (FA)/caesium (FA)yCs1–yPb(IxBr1–x)3 perovskite system. A population of encapsulated devices showed improved operational stability, with a median T80 lifetime (the time over which the device power conversion efficiency decreases to 80% of its initial value) for the steady-state power conversion efficiency of 1,190 hours, and a champion device showed a T80 of 1,410 hours, under simulated sunlight at 65 °C in air, under open-circuit conditions. This work highlights the importance of material quality in achieving the long-term operational stability of perovskite optoelectronic devices.

Abstract:

Despite the incredible progress made, the highest efficiency perovskite solar cells are still restricted to small areas (<1 cm2). In large part, this stems from a poor understanding of the widespread spatial heterogeneity in devices. Conventional techniques to assess heterogeneities can be time consuming, operate only at microscopic length scales, and demand specialized equipment. We overcome these limitations by using luminescence imaging to reveal large, millimeter-scale heterogeneities in the inferred electronic properties. We determine spatially resolved maps of “charge collection quality”, measured using the ratio of photoluminescence intensity at open and short circuit. We apply these methods to quantify the inhomogeneities introduced by a wide range of transport layers, thereby ranking them by suitability for upscaling. We reveal that top-contacting transport layers are the dominant source of heterogeneity in the multilayer material stack. We suggest that this methodology can be used to accelerate the development of highly efficient, large-area modules, especially through high-throughput experimentation.