mesoporous stack-titania (m-TiO 2 ), zirconia (ZrO 2 ), carbon (C)-is printable, C-PSCs are ideal for large scale production and, interestingly, some features that prevent degradation, i.e., lack of metal cathode [9] and organic HTM, [10] are also responsible for the simpler manufacturing process, paving the way for C-PSCs to move quickly from the lab to the market. This module architecture not only uses low-cost materials but can be produced by equipment that has a very low-capital cost thus reducing the barrier to commercialization of perovskite modules. Constraining the grain growth of the perovskite completely within the three mesoporous structures enables crystallization of the perovskite over large areas without the need for dynamic drying [11,12] to mimic the spin coating process. [13] There have been some reports demonstrating that C-PSC modules can be produced by screen printing, via registration of the overlapping layers, and can deliver between 10 and 11% power conversion efficiency (PCE) on 10 × 10 cm 2 substrates, with active areas ranging from 47.6 [7,14] to 70 cm 2 , [15] and, in particular, showing over 1 year stability under illumination, as reported by Grancini et al. [7] These results for C-PSC modules are even more remarkable, considering that modules with comparable active areas (>45 cm 2 ) and different device architecture, yielded respectively 12.6% PCE on 50.6 cm 2 (FTO/c-TiO 2 /graphene+m-TiO 2 / GO-Li/perovskite/spiro-OMeTAD/Au), [16] 8.7% PCE on 60 cm 2 (ITO/PEDOT:PSS/perovskite/PCBM/Au), [17] and 4.3% PCE on 100 cm 2 (FTO/c-TiO 2 /m-TiO 2 /perovskite/spiro-OMeTAD/ Au) [11] ; moreover, the record for PSC modules overall is Microquanta's 16% PCE [18,19] on just 16.29 cm 2 aperture area (active area + dead area for interconnections).Upscaling C-PSC manufacture from 10 × 10 cm 2 to larger substrate dimensions, e.g., A4 size as in our case, is far from trivial. Spraying the TiO 2 blocking layer (BL) at temperatures as high as 300 °C causes the large substrates to crack in the worst case or to bend, compromising the thickness homogeneity over the substrate of the printed layers, mostly and more crucially for the thinnest of the three, the sub-micrometric m-TiO 2 . Any change in the layers' thickness across the substrate can affect the performance of individual cells constituting the module Perovskite solar cells based on an all printable mesoporous stack, made of overlapping titania, zirconia, and carbon layers, represent a promising device architecture for both simple, low-cost manufacture, and outstanding stability. Here a breakthrough in the upscaling of this technology is reported: Screen printed modules on A4 sized conductive glass substrates, delivering power conversion efficiency (PCE) ranging from 3 to 5% at 1 sun on an unprecedented 198 cm 2 active area. An increase in the PCE, due to higher V OC and fill factor, is demonstrated by patterning the TiO 2 blocking layer. Furthermore, an unexpected increase of the performance is observed over time, while storing the modules in the dark,...

Since the discovery of the record figure of merit (ZT) of 2.6 ± 0.3 in tin selenide (SnSe), the material has attracted much attention in the field of thermoelectrics. This paper reports a novel pseudo‐3D printing technique to fabricate bulk SnSe thermoelectric elements, allowing for the fabrication of standard configuration thermoelectric generators. In contrast to fabrication examples presented to date, this technique is potentially very low‐cost and allows for facile, scalable, and rapid fabrication. Bulk SnSe thermoelectric elements are produced and characterized over a wide range of temperatures. An element printed from an ink with 4% organic binder produces the highest performance, with a ZT value of 1.7 (±0.25) at 758 K. This is the highest ZT reported of any printed thermoelectric material, and the first bulk printed material to operate at this temperature. Finally, a proof‐of‐concept, all printed SnSe thermoelectric generator is presented, producing 20 µW at 772 K.

SummaryPhotovoltaic devices based on perovskite materials have a great potential to become an exceptional source of energy while preserving the environment. However, to enter the global market, they require further development to achieve the necessary performance requirements. The environmental performance of a pre-industrial process of production of a large-area carbon stack perovskite module is analyzed in this work through life cycle assessment (LCA). From the pre-industrial process an ideal process is simulated to establish a benchmark for pre-industrial and laboratory-scale processes. Perovskite is shown to be the most harmful layer of the carbon stack module because of the energy consumed in the preparation and annealing of the precursor solution, and not because of its Pb content. This work stresses the necessity of decreasing energy consumption during module preparation as the most effective way to reduce environmental impacts of perovskite solar cells.

Roll-to-roll coating of all active layers is demonstrated for a P–I–N perovskite solar cell stack, using a single step perovskite ink with an acetonitrile solvent system and flexible plastic substrate.

Low viscosity rapid drying perovskite formulations designed to give high quality solar films when slot-die coated on flexible roll-to-roll compatible substrates are developed .

Perovskite photovoltaics have shown great promise in device efficiency but also the promise of scalability through solution‐processed manufacture. Efforts to scale perovskites have been taken through printable mesoporous scaffolds and slot die coating of flexible substrates roll‐to‐roll (R2R). However, to date there has been no demonstration of entirely R2R‐coated devices due to the lack of a compatible solution‐processable back electrode; instead, high‐value evaporated metal contacts are employed as a post process. Here, in this study, the combination of a low‐temperature device structure and R2R‐compatible solution formulations is employed to make a fully R2R printable device architecture overcoming interlayer incompatibilities and recombination losses. Therefore, the n–i–p device structure of SnO2/perovskite/poly(3,4‐ethylenedioxythiophene)/carbon is employed to form an ohmic contact between a p‐type semiconductor and printable carbon electrode. In particular, the results show that the small‐scale device efficiencies of 13–14% are achieved, matching the device performance of evaporated gold electrodes. Also, this entirely R2R‐coated perovskite prototype represents a game changer, reaching over 10% (10.8) stabilized power conversion efficiency with unencapsulated long‐term stability retaining 84% of its original efficiency over 1000 h under 70% RH and 25 °C.

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Abstract:Roll-to-roll slot-die coating with a meniscus guide is used to deposit several layers in a P-I-N perovskite solar cell stack, including the perovskite layer. The use of various length meniscus guides as part of the slot-die head allows controlled coating of these layers at a common coating speed. The length of meniscus guide used is optimised and related to the rheology of the coated ink and appropriate choice of meniscus guide length provides a way to avoid flooding of the coated area and improve coating definition. Initial coating trial results suggest the low-flow limit of slot-die coating is still applicable when using a meniscus guide, which is an important and previously unreported observation, application of this theory to meniscus guide coating provides a useful tool for rapidly determining the appropriate coating conditions that can be used as part of a manufacturing process. This is further explored through the deposition of perovskite solar cells by roll-to-roll slot-die coating. The perovskite layer is deposited using a sequential slot-die deposition process using a low toxicity dimethyl sulfoxide ink for the lead iodide layer, it is found that increasing the drying oven temperature and air flow rate can be used to improve the uniformity of the layer but this can also result in deformation of the plastic substrate. Functioning perovskite solar cells are demonstrated using this technique, but a large variation is found between device performances which is attributed to the poor uniformity of the perovskite layer and damage caused to the substrate by excessive heating.