Thermal nanoimprint to improve the morphology of MAPbX3 (MA = methylammonium, X = I or Br)

Mayer, André; Buchmüller, Maximilian; Wang, Si; Steinberg, Christian; Papenheim, Marc; Scheer, Hella-Christin; Pourdavoud, Neda; Haeger, Tobias; Riedl, Thomas

doi:10.1116/1.4991619

Cited by 23 publications

(53 citation statements)

References 37 publications

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“…The average roughness of the AFM scans is displayed in Figure b. The optimum in device performance is found at 90 °C, which is in line with temperatures used for nanoimprinted perovskite layers . Here, the perovskite recrystallizes to very smooth layers with root mean square (RMS) roughness around 3.1 nm (see Figure a,b).…”

Section: Resultssupporting

confidence: 59%

Laminated Perovskite Photovoltaics: Enabling Novel Layer Combinations and Device Architectures

Schmager

Roger

Schwenzer

et al. 2020

Adv Funct Materials

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High‐efficiency perovskite‐based solar cells can be fabricated via either solution‐processing or vacuum‐based thin‐film deposition. However, both approaches limit the choice of materials and the accessible device architectures, due to solvent incompatibilities or possible layer damage by vacuum techniques. To overcome these limitations, the lamination of two independently processed half‐stacks of the perovskite solar cell is presented in this work. By laminating the two half‐stacks at an elevated temperature (≈90 °C) and pressure (≈50 MPa), the polycrystalline perovskite thin‐film recrystallizes and the perovskite/charge transport layer (CTL) interface forms an intimate electrical contact. The laminated perovskite solar cells with tin oxide and nickel oxide as CTLs exhibit power conversion efficiencies of up to 14.6%. Moreover, they demonstrate long‐term and high‐temperature stability at temperatures of up to 80 °C. This freedom of design is expected to access both novel device architectures and pairs of CTLs that remain usually inaccessible.

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Section: Resultssupporting

confidence: 59%

Laminated Perovskite Photovoltaics: Enabling Novel Layer Combinations and Device Architectures

Schmager

Roger

Schwenzer

et al. 2020

Adv Funct Materials

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“…For this purpose, the layer is covered with a flat stamp and treated with temperature and pressure. An adequate imprint temperature is 150 °C which is markedly higher than usual annealing temperatures for perovskite layers [17,18]. So far it seems that during imprint the stamp protects the layer from the surrounding atmosphere and avoids the evaporation of volatile components, thus hindering degradation.…”

Section: Introductionmentioning

confidence: 99%

Upgrading of methylammonium lead halide perovskite layers by thermal imprint

et al. 2021

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The manufacturing of devices from methylammonium-based perovskites asks for reliable and scalable processing. As solvent engineering is not the option of choice to obtain homogeneous layers on large areas, our idea is to ‘upgrade’ a non-perfect pristine layer by recrystallization in a thermal imprint step (called ‘planar hot pressing’) and thus to reduce the demands on the layer formation itself. Recently, imprint has proven both its capability to improve the crystal size of perovskite layers and its usability for large area manufacturing. We start with methylammonium lead bromide layers obtained from a conventional solution-based process. Acetate is used as a competitive lead source; even under perfect conditions the resulting perovskite layer then will contain side-products due to layer formation besides the desired perovskite. Based on the physical properties of the materials involved we discuss the impact of the temperature on the status of the layer both during soft-bake and during thermal imprint. By using a special imprint technique called ‘hot loading’ we are able to visualize the upgrade of the layer with time, namely a growth of the grains and an accumulation of the side-products at the grain boundaries. By means of a subsequent vacuum exposition we reveal the presence of non-perovskite components with a simple inspection of the morphology of the layer; all experiments are supported by X-ray and electron diffraction measurements. Besides degradation, we discuss recrystallization and propose post-crystallization to explain the experimental results. This physical approach towards perovskite layers with large grains by post-processing is a key step towards large-area preparation of high-quality layers for device manufacturing.

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“…[44] Nanoimprint Lithography: mr-I T85-0.3 was spin coated on the perovskite films at 4000 RPM and baked for 2 min on a hotplate at 100 °C to generate ≈ 280 nm thick films. [18,36] Reactive Ion Etching: Since the NIL step leaved a residual layer at the areas that were to be milled, oxygen plasma was required in order to reach the perovskite in these areas (Figure 3d). Then, the imprint pressure was raised to 25 bar for duration of 5 min followed by cooling of the system (≈5 min) to reach a final temperature of 60 °C.…”

Section: Methodsmentioning

confidence: 99%

“…[18,[35][36][37] The later approach enables the patterning of perovskite films by directly imprinting a mold into the material at elevated temperatures. [18,[35][36][37] The later approach enables the patterning of perovskite films by directly imprinting a mold into the material at elevated temperatures.…”

Section: Introductionmentioning

confidence: 99%

Micro Lasers by Scalable Lithography of Metal‐Halide Perovskites

Bar‐On

Brenner

Lemmer

et al. 2018

Adv Materials Technologies

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description of the efforts on developing perovskite lasers is given in recent review articles. [19][20][21][22] As the field advances, new approaches for patterning perovskite films are becoming essential. More specifically, a lithographic approach that can define desired perovskite patterns is highly needed in order to utilize these materials for the realization of integrated perovskite photonic devices. Generally speaking, effective lithographic patterning requires three main capabilities. First, the ability to cover the material (in our case perovskites) with a layer of resist and pattern it with sub-micrometer resolution using a scalable process. Second, employment of the patterned resist as an etch mask for complete removal of the unprotected perovskite film. Third, removal of the residual resist mask from the perovskite film. Since metal halide perovskites are unstable soluble materials that are sensitive to a variety of solvents and gases, [23] accomplishing all of the above steps without damaging the film is highly challenging. During the past few years, several attempts have been made in order to address this challenge. Lyashenko et al. [24] demonstrated the ability to pattern perovskites using photolithography followed by SF 6 etching. This approach was utilized to define patterns in photoresists on top of methyl-ammonium lead iodide (MAPbI 3 ) films but was limited to micrometer scale features due to diffraction effects in photolithography. In addition, the chemical reaction that was used in order to etch the material only modified the exposed areas chemically (converting the material to PbF 2 ) and did not remove the perovskite layer completely as desired from a proper etching technique. Zhang et al. [25] demonstrated a different approach where PMMA layers were deposited on top of a MAPbBr 3 film and patterned using electron beam lithography (EBL) followed by dry Cl etching. Although this method can potentially generate sub-micrometer features, it is based on a serial patterning technique (EBL) and is thus limited in terms of speed and cost. In addition, the scanning electron microscopy (SEM) images of the patterned surface suggest that the etching process left a residual layer on the surface (possibly PbCl 2 ) and was unable to remove the perovskite completely. A slightly different approach to pattern perovskite films, involving lift-off instead of etching, was recently successfully demonstrated. [26] However, this technique necessitates the evaporation of perovskite films and is not compatible with the standard spin-coating film preparation method which is simple, inexpensive, and renders these materials A complete lithographic scheme for thin metal halide perovskite films is demonstrated and utilized for the realization of perovskite micro lasers. The process consists of nanoimprint lithography followed by ion beam milling. It is simple, fast, scalable, and exhibits sub-micrometer resolution. The optical properties of the perovskite films are obtained by employing analytical tools as well as by cha...

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Thermal nanoimprint to improve the morphology of MAPbX3 (MA = methylammonium, X = I or Br)

Cited by 23 publications

References 37 publications

Laminated Perovskite Photovoltaics: Enabling Novel Layer Combinations and Device Architectures

Laminated Perovskite Photovoltaics: Enabling Novel Layer Combinations and Device Architectures

Upgrading of methylammonium lead halide perovskite layers by thermal imprint

Micro Lasers by Scalable Lithography of Metal‐Halide Perovskites

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