Multiscale morphology design of hybrid halide perovskites through a polymeric template

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Each component layer in a perovskite solar cell plays an important role in the cell performance. Here, a few types of polymers including representative p‐type and n‐type semiconductors, and a classical insulator, are chosen to dope into a perovskite film. The long‐chain polymer helps to form a network among the perovskite crystalline grains, as witnessed by the improved film morphology and device stability. The dewetting process is greatly suppressed by the cross‐linking effect of the polymer chains, thereby resulting in uniform perovskite films with large grain sizes. Moreover, it is found that the polymer‐doped perovskite shows a reduced trap‐state density, likely due to the polymer effectively passivating the perovskite grain surface. Meanwhile the doped polymer formed a bridge between grains for efficient charge transport. Using this approach, the solar cell efficiency is improved from 17.43% to as high as 19.19%, with a much improved stability. As it is not required for the polymer to have a strict energy level matching with the perovskite, in principle, one may use a variety of polymers for this type of device design.

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confidence: 99%

Polymer Doping for High‐Efficiency Perovskite Solar Cells with Improved Moisture Stability

Jiang

Wang

Jin

et al. 2017

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224

“…[8] As a unique event in the landscape of solar energy harvesting, perovskite solar cells have experienced an increment of their power conversion efficiency by ≈8% (from 13.4% to 23.7%) in the last 5 years. Solutions to guarantee the durability of products are mandatory and can be numerous, if the problem is addressed from different perspectives.Within the possible approaches to stabilize the perovskite lattice and its behavior under illumination, recent efforts have focused on introducing various treatments, [11,12] molecules, or additives, [13][14][15][16][17][18][19] through different procedures. However, the well-known structural instability of hybrid perovskites under working conditions limits a real market uptake of all the related technologies.…”

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confidence: 99%

“…Within the possible approaches to stabilize the perovskite lattice and its behavior under illumination, recent efforts have focused on introducing various treatments, [11,12] molecules, or additives, [13][14][15][16][17][18][19] through different procedures. Nitrogen has been also exploited as inert species [20][21][22][23][24] but its role is still unfocused.…”

mentioning

confidence: 99%

Nitrogen Soaking Promotes Lattice Recovery in Polycrystalline Hybrid Perovskites

Alberti

Deretzis

Mannino

et al. 2019

Self Cite

wide dissemination, and high technological throughput. [8] As a unique event in the landscape of solar energy harvesting, perovskite solar cells have experienced an increment of their power conversion efficiency by ≈8% (from 13.4% to 23.7%) in the last 5 years. [9,10] This technology is expected to successfully contribute to the enormous challenge of future power supply from sustainable energy sources. However, the well-known structural instability of hybrid perovskites under working conditions limits a real market uptake of all the related technologies. Solutions to guarantee the durability of products are mandatory and can be numerous, if the problem is addressed from different perspectives.Within the possible approaches to stabilize the perovskite lattice and its behavior under illumination, recent efforts have focused on introducing various treatments, [11,12] molecules, or additives, [13][14][15][16][17][18][19] through different procedures. Nitrogen has been also exploited as inert species [20][21][22][23][24] but its role is still unfocused. The existing (direct or indirect) findings in the literature stimulate the idea of beneficially using N 2 molecules in technological solutions, if their role is persuasively afforded. [25] N 2 molecules are small, safe, and easy to apply.Related to the material stability, we emphasize that the plethora of perovskites produced in different laboratories, with preparation procedures changing from lab to lab and from time to time, ask for treatments that take care and, in a certain extent, reset the starting conditions in a convenient and reproducible manner. This is particularly needed for small grained perovskite layers, on one hand used to implement pinhole-free coverages, but, on the other hand, offering extended lattice discontinuities due to the high surface to volume ratio. In addition to morphology and environment, temperature-related effects are unavoidable during device operation. [24,26] A rationalization of the phenomena needs to embody heating and thermal cycles to preserve the material integrity and/or the structural reversibility versus temperature.In this framework, we argue that nitrogen species have an active role in the stabilization of all the exposed methylammonium lead iodide (MAPbI 3 ) surfaces via their action at grain shells. This conclusion is independent of the particular On the basis of experiment and theory, a general paradigm is drawn that reconsiders N 2 not simply being an inert species but rather an effective healing gas molecule if entering a methylammonium lead iodide (MAPbI 3 ) layer. Nitrogen is soaked into polycrystalline MAPbI 3 via a postdeposition mild thermal treatment under slightly overpressure conditions to promote its diffusion across the whole layer. A significant reduction of radiative recombination and a concurrent increase of light absorption, with a maximum benefit at 80 °C, are observed. Concomitantly, the current of holes drawn from the surfaces with nanometer resolution through a biased tip is raised by a factor of 3 un...

“…Various strategies, such as thermal annealing, [13,14] additive inclusion, [15][16][17][18] modification of precursor concentrations and carrier solvents [19,20] and high-temperature-casting [21] have been investigated so far to control perovskite structure, grain size, degree of crystallinity and stability to moisture -however with varying success. [21,22] Here, we introduce the use of commercially available, low molecular-weight organic gelators (LMOGs) LMGOs are commonly used additives in the commodity plastics area because they promotealready at minute quantities -gelation of polymer solutions or melts upon cooling while they have no effect on these systems at elevated temperatures.…”

Section: Introductionmentioning

confidence: 99%

Organic Gelators as Growth Control Agents for Stable and Reproducible Hybrid Perovskite‐Based Solar Cells

Masi

Rizzo

Munir

et al. 2017

Self Cite

Article type: Full paperOrganic gelators as growth control agents for stable and reproducible hybrid perovskite-based solar cells Sofia Masi, [a] Aurora Rizzo, [a] Rahim Munir, [b] Andrea Listorti, [a,c] Antonella Giuri, [d] Carola Esposito Corcione, [d] Neil D. Treat, [e] Giuseppe Gigli, [a,c] Aram Amassian, [b] * Natalie Stingelin, [e,f] * and Silvia Colella* [a,c] Low molecular-weight organic gelators are widely used to influence the solidification of polymers, with applications ranging from packaging items, food containers to organic electronic devices, including organic photovoltaics. Here, this concept is extended to hybrid halide perovskite-based materials. In-situ time-resolved grazing incidence wide angle x-ray scattering (GIWAXS) measurements performed during spin-coating reveal that organic gelators beneficially influence the nucleation and growth of the perovskite precursor phase. This can be exploited for the fabrication of planar n-i-p heterojunction devices with MAPbI3 (MA = CH3NH3 + ) that display a performance that not only is enhanced by ∼25% compared to solar cells where the active layer was produced without the use of a gelator but that also feature a higher stability to moisture and a reduced hysteresis. Most importantly, the presented approach is straight-forward and simple, and it provides a general method to render the film-formation of hybrid perovskites more reliable and robust, analogous to the control that is afforded by these additives in the processing of commodity 'plastics'.