Can Laminated Carbon Challenge Gold? Toward Universal, Scalable, and Low‐Cost Carbon Electrodes for Perovskite Solar Cells

Abstract

While perovskite solar cell (PSC) efficiencies are soaring at a laboratory scale, these are most commonly achieved with evaporated gold electrodes, which would present a significant expense in large‐scale production. This can be remedied through the use of significantly cheaper carbon electrodes that, in contrast to metals, also do not migrate through the device. To this end, the present work investigates simple‐to‐prepare aluminum‐supported carbon electrodes derived from commercially available, inexpensive materials that can be applied onto various hole‐transporting materials and enable photovoltaic performances on par with those provided by gold electrodes. Successful integration of the new carbon‐based electrode into flexible devices produced by a roll‐to‐roll printing technology by both pressing and lamination is demonstrated. However, temperature cycling durability tests reveal that the use of carbon electrodes based on commercial pastes is hindered by incompatibility of adhesive additives with the key components of the PSCs under heating. Resolving this issue, tailor‐made graphite electrodes devoid of damaging additives are introduced, which improve the PSC stability under temperature cycling test protocol to the level provided by benchmark gold electrodes. The study highlights current challenges in developing laminated carbon electrodes in PSCs and proposes strategies toward the resolution thereof.

Solution Processable Direct Bandgap Copper‐Silver‐Bismuth Iodide Photovoltaics: Compositional Control of Dimensionality and Optoelectronic Properties

“…A recently developed cheap adhesive carbon counter electrode [ 33 ] was used herein and provided significantly better performance than conventional evaporated gold (Figure S23 and Table S4, Supporting Information). This might be possibly attributed to the penetration of evaporated gold through the nanoscale pin‐holes within a HTM layer and further through the active layer stimulating the Ag + or Cu + ion migration.…”

“…Silver paste (CP1 30J) from ChipQuick and a 12 µm thick domestic grade all‐purpose aluminum foil from Castaway Caterers Foil Australia were used as purchased to improve the contact of carbon electrodes. [ 33 ]…”

“…Adhesive carbon electrodes with a thickness of ≈25 µm were prepared following the reported procedure. [ 33 ] Briefly, the electrode was deposited onto a copper‐coated aluminum substrate by automated doctor blading (MTVmesstechnik CX202) of ≈ 5 mg cm −2 of the Jelcon CH‐8 paste at a rate of 9 mm s −1 and height adjusted to 80 µm. The resulting electrodes were immersed in stirred ethanol for 30 min to remove additives in the commercial carbon paste and dried in the ambient environment for 2 h at 65 °C.…”

“…Silver paste (CP1 30J) from ChipQuick and a 12 µm thick domestic grade all-purpose aluminum foil from Castaway Caterers Foil Australia were used as purchased to improve the contact of carbon electrodes. [33] Photovoltaic Device Fabrication: Cleaning of the pre-patterned FTOcoated glass substrates included sequential ultrasonication (Elmasonic S 300H bath at an operating power of 1500 W) in a 2 wt% Helmanex surfactant solution, water, and ethanol (15 min in each medium), drying under N 2 flow, and plasma treatment at 1000 mTorr for 10 min (Harrick Plasma cleaner PDC-002 at maximum power). A 15 nm thick compact titania blocking layer (c-TiO 2 ) was formed on a cleaned FTO substrate surface using a custom-made automatic spray pyrolysis system by depositing a 5 vol% TAA precursor in anhydrous isopropanol at 500 °C (heated by high-precision hot-plate Harry Gestigkeit GmbH PZ28-3TD) for 30 min.…”

CuSCN as a hole transport layer in an inorganic solution-processed planar Sb2S3solar cell, enabling carbon-based and semitransparent photovoltaics

“…This observation had been reported elsewhere, using carbon electrodes. 53 The carbon electrode reflects barely any light (<5% reflectance for all wavelengths in Figure 3b). At the same time, the ultrathin Sb 2 S 3 absorber layer cannot absorb all the light, especially the longer wavelengths (as can be seen in Figure S3a, the absorption coefficient of Sb 2 S 3 drops steeply in the longer wavelength region).…”