Commercializing perovskite-based tandems necessitates environmentally friendly solvents for scalable fabrication of efficient wide-bandgap (WBG) (1.65–1.80 eV) perovskites. However, the green solvents developed for formamidinium lead iodide-based ~1.50-eV-bandgap perovskites are unsuitable for WBG perovskites due to the low solubility of caesium and bromide salts, leading to reliance on toxic N,N-dimethylformamide solvent. Here we present a green solvent system comprising dimethyl sulfoxide and acetonitrile to effectively dissolve the named salts, with the addition of ethyl alcohol to prevent precursor degradation and to extend the solution processing window. Using this green solvent mixture, we achieve blade-coated WBG perovskite solar cells with power conversion efficiencies of 19.6% (1.78 eV) and 21.5% (1.68 eV). We then demonstrate 20.25-cm2 all-perovskite tandem solar modules with a power conversion efficiency of 23.8%. Furthermore, we achieved WBG perovskites deposited in ambient air and narrow-bandgap perovskites fabricated using the same green solvents, which promotes the viability of environmentally friendly fabrication.
The formation of a homogeneous passivation layer based on phase-pure two-dimensional (2D) perovskites is a challenge for perovskite solar cells, especially when upscaling the devices to modules. Here we reveal a chain-length-dependent and halide-related phase separation problem of 2D perovskite growing on top of three-dimensional perovskites. We demonstrate that a homogeneous 2D perovskite passivation layer can be formed upon treatment of the perovskite layer with formamidinium bromide in long-chain ( >10) alkylamine ligand salts. We achieve champion active-area efficiencies of 25.61%, 24.62% and 23.60% for antisolvent-free processed small- (0.14 cm2) and large-size (1.04 cm2) devices and mini-modules (13.44 cm2), respectively. This passivation strategy is compatible with printing technology, enabling champion aperture-area efficiencies of 18.90% and 17.59% for fully slot-die printed large solar modules with areas of 310 cm2 and 802 cm2, respectively, demonstrating the feasibility of the upscaling manufacturing.
Small modular reactors (SMRs) offer a unique solution to the challenge of decarbonizing mid- and high-temperature industrial processes. Here we develop deployment pathways for four SMR designs displacing natural gas in industrial heat processes at 925 facilities across the United States under diverse policy and factory or onsite learning conditions. We find that widespread SMR deployment in industry requires gas prices above US$6 per metric million British thermal unit, low capital cost over-runs and/or aggressive carbon taxes. At gas prices of US$6–10 per metric million British thermal unit, 7–55 gigawatt-thermal (GWt) of SMRs could be economically deployed by 2050, reducing annual emissions by up to 59 Mt of CO2-equivalent. Of this deployment, 2–24 GWt rely on module manufacturing learning within a factory. Widespread deployment potential hinges on avoiding substantial cost escalation for early investments. Policy levers such as direct subsidies are not effective at incentivizing sustainable deployment, but aggressive carbon taxes and investment tax credits provide effective support for SMR success.
Microscopy provides a proxy for assessing the operation of perovskite solar cells, yet most works in the literature have focused on bare perovskite thin films, missing charge transport and recombination losses present in full devices. Here we demonstrate a multimodal operando microscopy toolkit to measure and spatially correlate nanoscale charge transport losses, recombination losses and chemical composition. By applying this toolkit to the same scan areas of state-of-the-art, alloyed perovskite cells before and after extended operation, we show that devices with the highest macroscopic performance have the lowest initial performance spatial heterogeneity—a crucial link that is missed in conventional microscopy. We show that engineering stable interfaces is critical to achieving robust devices. Once the interfaces are stabilized, we show that compositional engineering to homogenize charge extraction and to minimize variations in local power conversion efficiency is critical to improve performance and stability. We find that in our device space, perovskites can tolerate spatial disorder in chemistry, but not charge extraction.