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.
Scalable coating
methods have recently emerged as practical alternative deposition
techniques to the conventional spin-coating despite their lower yielding
power conversion efficiencies (PCEs). The most important barrier acting
against the use of scalable deposition methods to get a highly absorbing
(>95%) film with controlled morphology in the high crystallinity
of perovskite particles is the impossibility of antisolvent dripping
during the deposition. Here, we demonstrate the positive role of both
the surfactant-engineering and the vacuum-annealing (<100 Pa) process
in improving the device performance to overcome this limit. A detailed
optimization of the vacuum-assisted meniscus printing parameters is
discussed to get a pinhole-free triple-cation mixed-halide perovskite
layer with high crystallinity. In particular, the results showed that
with the increase in surface coverage, wettability and perovskite
crystallinity were achieved by adding Triton X-100 (12.5 mM) as a
surfactant into the precursor solution. The perovskite devices with
the optimized precursor ink formula and optimized meniscus printing
parameters showed a PCE of 15.1 and 12.3 with the active area of 0.09
cm2 and 1 cm2, respectively. Consequently, the
obtained results suggested that perovskite cells made by this vacuum-assisted
printing technique and the precursor system could lead to the improved
device performance and reproducibility in a high humidity (70–90%)
environment.
TiO 2 nanoparticle (NP), composite TiO 2 nanoparticle-nanorod (NP-NR) and bi-layer TiO 2 nanoparticle/nanorod (NP/NR) with the optimized diameter of NRs had been prepared as anode layer in dye-sensitized solar cells (DSSCs). Morphology and thickness of anode layers were provided by field emission scanning electron microscope (FE-SEM) and scanning electron microscopy (SEM) devices. Current density-voltage diagrams were prepared by potentiostat and solar simulator devices at air mass (AM) 1.5. It is determined that DSSCs based on composite NP-NR photoelectrode had the best conversion efficiency of 5.07%. Also, the results of the electrochemical modelling of these DSSCs indicated that solar cells based on NP-NR electrode had the highest electron transport time (τ d) of 312.87 ms, electrons' recombination lifetime (τ n) of 130.4 ms and the lowest transfer resistance (R ct) as well as transport resistance (R t) of 22.46 and 9.4 , respectively.
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