All‐Printed Roll‐to‐Roll Perovskite Photovoltaics Enabled by Solution‐Processed Carbon Electrode

Abstract

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.

Circular economy for perovskite solar cells – drivers, progress and challenges

“…85 Tremendous progress in scale-up has been achieved with a variety of material sets, production processes and cell architectures reported, in a race to stabilise the perovskite layer for viable commercialisation. 86 Common cell architectures are presented in Fig. 4, generally comprised of a transparent conductive substrate such as transparent conductive oxide (TCO) coated glass or polyethylene terephthalate (PET) onto which an electron transport layer (ETL, usually TiO 2 ), 87,88 the perovskite, hole transport layer (HTL) and metallic contacts (typically Au via thermal evaporation) are sequentially deposited.…”

“…The lowest impact cells considered in this study use Ag or C. Both have lower embodied impacts than Au (Table 3), but Ag still contributes considerably to overall production impacts due to energy consumption in its deposition, whereas carbon may represent a lower impact deposition option with R2R solution deposition recently demonstrated. 86 Final selection must be justified considering overall cell performance and net benefits afforded following consideration of avoided use of grid electricity. Should Au prove to be the most beneficial choice overall, circular economy strategies to retain Au in successive generations of PSMs will be important to mitigate ongoing impacts associated with its primary production and meet increasing demand from PSC technologies as deployment scales.…”

“…R2R production of carbon electrodes in perovskite modules that avoid Au use has been demonstrated. 86 P–I–N architectures also avoid the use of Au contacts.…”

Fabrication of low-cost and flexible perovskite solar cells by slot-die coating for indoor applications

“…11 Also, the latter devices could maintain B85% of their initial efficiency after 1000 h under 70% relative humidity with no encapsulation. 11 However, there is currently no available data on the efficiency of flexible PSCs deposited exclusively by scalable deposition methods under indoor lighting conditions.…”

“…9 If considering only flexible substrates and processing under ambient atmosphere, moderately high efficiencies are still possible: in 2020, Watson's group reported a 13.4% efficiency for an n–i–p PSC with slot-die coated extraction layers and perovskite, and an evaporated electrode; 10 while in 2023, the same group reported a 9.7% efficiency for a fully slot-die-coated device with a carbon-based electrode. 11 Also, the latter devices could maintain ∼85% of their initial efficiency after 1000 h under 70% relative humidity with no encapsulation. 11 However, there is currently no available data on the efficiency of flexible PSCs deposited exclusively by scalable deposition methods under indoor lighting conditions.…”