Using microgels to control the morphology and optoelectronic properties of hybrid organic–inorganic perovskite films

Dokkhan, Chotiros; Mokhtar, Muhamad Z.; Chen, Qian; Saunders, Brian R.; Hodson, Nigel; Hamilton, B.

doi:10.1039/c8cp05148h

Cited by 10 publications

(26 citation statements)

References 59 publications

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“…121,122 However, the thermal stability can be increased by fully replacing iodide with bromide. 123,124 In fact, CsPbBr 3 is stable till 580 1C 125 and presents great charge transport ability and mean free path. 126 This perovskite was used in planar PSCs and showed a remarkable stability for more than three months in humid air.…”

Section: High-temperature Processed Front Electrodesmentioning

confidence: 99%

Carbon-based materials for stable, cheaper and large-scale processable perovskite solar cells

Fagiolari

Bella

2019

Energy Environ. Sci.

260

188

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Almost ten years after their first use in the photovoltaic (PV) field, perovskite solar cells (PSCs) are now hybrid devices that, in addition to having reached silicon performance, can accelerate the energy transition and boost the use of abundant elements for their manufacturing process. However, noble metals (in particular gold) represent the most typically used sources for back electrode fabrication, and this issue has been intensively considered by the research community in the last five years. This review shows how the most promising solution, considering also the need to develop a large-scale production process, is based on the use of carbon-based materials for the preparation of back electrodes. Graphite, carbon black, graphene and carbon nanotubes (CNTs) have been proposed, functionalized and characterized, leading to laboratory-scale solar cells and modules capable of providing excellent efficiencies and ensuring stability greater than those of gold-based devices. Strengthened by these results and its hydrophobizing properties, carbon has also started to be used as an electron transporting material (ETM), with excellent results on both rigid and flexible substrates. This review discusses the major advances and the updated state-of-the-art in the carbon-based PSC scenario, keeping a solid trajectory where the accessibility, low cost, high electrical conductivity, chemical stability and controllable porosity of carbon are highlighted and exploited in the design of upscalable hybrid solar cells. Broader contextToday, more than 75% of the world energy demand is met by traditional, non-sustainable energy resources, mainly based on coal, natural gas and oil. Photovoltaics represents a concrete action to mitigate fossil fuel consumption, and among all the developed solar cells, perovskite-based ones have shown the highest increase in terms of efficiency (currently above 25%). Halide perovskites, as a family of new-generation semiconductor materials, are also exploitable for light-emitting devices, photodetectors and memristors, but their use in photovoltaics gives rise to outstanding performances. Here, photogenerated charges pass through electron/hole transporting materials and are transferred to the external circuit by front and back electrodes. While the front electrode is a common conductive glass, many issues are now under study concerning the back electrode, traditionally made of gold. Indeed, replacing this expensive metal with a much cheaper alternative is vital for realizing affordable solar technologies. Carbon, in its multiple forms, represents the winning solution and the scientific community has recently shown its large scale processability, its power as a stability booster and some interesting effects at the perovskite/electrode interface. This review shows how carbon is becoming the winning ingredient for the scaling up and worldwide diffusion of perovskite solar cells.

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Section: High-temperature Processed Front Electrodesmentioning

confidence: 99%

Carbon-based materials for stable, cheaper and large-scale processable perovskite solar cells

Fagiolari

Bella

2019

Energy Environ. Sci.

260

188

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“…Nowadays, these polymeric systems have attracted considerable attention in a large number of scientific and technological fields, such as nanotechnology, materials science, life sciences, and medicine . They have been applied in surface coating, drug accumulation and release, drug delivery, − optoelectronic switches, and many other applications. Among them, stimuli-responsive (smart) nanogels (gels with dimensions in the nanometer range) undergo a sharp and reversible volume phase transition (a conformational change that leads to a drastic variation in the degree of swelling) in a response to environmental stimuli, such as the change in temperature, pH, ionic strength, or solvent nature .…”

mentioning

confidence: 99%

Scaling Laws in the Diffusive Release of Neutral Cargo from Hollow Hydrogel Nanoparticles: Paclitaxel-Loaded Poly(4-vinylpyridine)

et al. 2020

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We study the nonequilibrium diffusive release of electroneutral molecular cargo encapsulated inside hollow hydrogel nanoparticles. We propose a theoretical model that includes osmotic, steric, and short-range polymer−cargo attractions to determine the effective cargo−hydrogel interaction, u eff *, and the effective diffusion coefficient of the cargo inside the polymer network, D eff *. Using dynamical density functional theory (DDFT), we investigate the scaling of the characteristic release time, τ 1/2 , with the key parameters involved in the process, namely, u eff *, D eff *, and the swelling ratio. This effort represents a full study of the problem, covering a broad range of cargo sizes and providing predictions for repulsive and attractive polymer shells. Our calculations show that the release time through repulsive polymer networks scales with q 2 e βu eff * /D eff * for βu eff * ≫ 1. In this case, the cargo molecules are excluded from the shell of the hydrogel. For attractive shells, the polymer retains the cargo molecules on its internal surface and its interior, and the release time grows exponentially with the attraction strength. The DDFT calculations are compared to an analytical model for the mean first passage time, which provides an excellent quantitative description of the kinetics for both repulsive and attractive shells without fitting parameters. Finally, we apply the method to reproduce experimental results on the release of paclitaxel from hollow poly(4-vinylpyridine) nanoparticles and find that the slow release of the drug can be explained in terms of the strong binding attraction between the drug and the polymer.

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“…In the earlier study, the MGs had a diameter of 913 nm and were deposited on the substrate causing the perovskite to crystallize in the inter-MG spaces. 35 We subsequently decreased the MG diameter to 336 nm and reported that that these smaller MGs were encapsulated within the perovskite matrix if the film thickness was larger than the MG diameter. 36 Here, we use much smaller NGs with a diameter of 40 nm.…”

Section: Introductionmentioning

confidence: 99%

Improving the Efficiency, Stability, and Adhesion of Perovskite Solar Cells Using Nanogel Additive Engineering

Altujjar

Mokhtar

Chen

et al. 2021

ACS Appl. Mater. Interfaces

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Additive engineering has been applied widely to improve the efficiency and/or stability of perovskite solar cells (PSCs). Most additives used to date are difficult to locate within PSCs as they are small molecules or linear polymers. In this work, we introduce, for the first time, carboxylic acid-functionalized nanogels (NGs) as additives for PSCs. NGs are swellable sub-100 nm gel particles. The NGs consist of poly(2-(2-methoxyethoxy) ethyl methacrylate)-co-methacrylic acid-co-ethylenegylcol dimethacrylate (PMEO 2 MA-MAA-EGD) particles prepared by a scalable synthesis, which have a diameter of 40 nm. They are visualized in the perovskite films using SEM and are located at the grain boundaries. X-ray photoelectron and FTIR spectroscopy reveal that the NGs coordinate with Pb 2+ via the −COOH groups. Including the NGs within the PSCs increased the grain size, decreased nonradiative recombination, and increased the power conversion efficiency (PCE) to 20.20%. The NGs also greatly increase perovskite stability to ambient storage, elevated temperature, and humidity. The best system maintained more than 80% of its original PCE after 180 days of storage under ambient conditions. Tensile cross-cut tape adhesion tests are used to assess perovskite film mechanical integrity. The NGs increased both the adhesion of the perovskite to the substrate and the mechanical stability. This study demonstrates that NGs are an attractive alternative to molecularly dispersed additives for providing performance benefits to PSCs. Our study indicates that the NGs act as a passivator, stabilizer, cross-linker, and adhesion promoter.

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Using microgels to control the morphology and optoelectronic properties of hybrid organic–inorganic perovskite films

Abstract: Spin coating mixed microgel/perovskite precursor solutions gives disordered inverse opal perovskite films with morphologies and optoelectronic properties that are controlled by the microgel particles.

Cited by 10 publications

References 59 publications

Carbon-based materials for stable, cheaper and large-scale processable perovskite solar cells

Carbon-based materials for stable, cheaper and large-scale processable perovskite solar cells

Scaling Laws in the Diffusive Release of Neutral Cargo from Hollow Hydrogel Nanoparticles: Paclitaxel-Loaded Poly(4-vinylpyridine)

Improving the Efficiency, Stability, and Adhesion of Perovskite Solar Cells Using Nanogel Additive Engineering

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