Materials Processing Routes to Trap-Free Halide Perovskites

Buin, Andrei; Pietsch, Patrick; Xu, Jixian; Voznyy, Oleksandr; Ip, Alexander H.; Comin, Riccardo; Sargent, Edward H.

doi:10.1021/nl502612m

Cited by 694 publications

(764 citation statements)

References 47 publications

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“…Because ARTICLE structural defects are known to play a crucial role in perovskite optical properties, 20,65,66 this weak PL intensity could be attributed to surface defects. In agreement with this idea, CH 3 NH 3 PbI 3 wires and rods made in the presence of the surface passivating n-octylammonium cation have a higher PL QYs of 1.7À1.4%, and their PL lifetimes inversely correlate with their aspect and surface-to-volume ratios (Table 1, see also Supporting Information).…”

Section: Resultsmentioning

confidence: 99%

Shape Evolution and Single Particle Luminescence of Organometal Halide Perovskite Nanocrystals

et al. 2015

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Organometallic halide perovskites CH 3 NH 3 PbX 3 (X = I, Br, Cl) have quickly become one of the most promising semiconductors for solar cells, with photovoltaics made of these materials reaching power conversion efficiencies of near 20%. Improving our ability to harness the full potential of organometal halide perovskites will require more controllable syntheses that permit a detailed understanding of their fundamental chemistry and photophysics. In this manuscript, we systematically synthesize CH 3 NH 3 PbX 3 (X = I, Br) nanocrystals with different morphologies (dots, rods, plates or sheets) by using different solvents and capping ligands. CH3NH3PbX3 nanowires and nanorods capped with octylammonium halides show relatively higher photoluminescence (PL) quantum yields and long PL lifetimes. CH3NH3PbI3 nanowires monitored at the single particle level show shape-correlated PL emission across whole particles, with little photobleaching observed and very few off periods. This work highlights the potential of low-dimensional organometal halide perovskite semiconductors in constructing new porous and nanostructured solar cell architectures, as well as in applying these materials to other fields such as light-emitting devices and single particle imaging and tracking.Keywords organometal halide perovskites, nanocrystals, preferred orientation, morphology control, size control, single particle photoluminescence Disciplines Chemistry CommentsReprinted (adapted) with permission from ACS Nano 9 (2015) 15,16 respectively, as well as high absorption coefficients. Critically, organolead perovskites have very long electronÀ hole carrier diffusion lengths, exceeding 1 μm in CH 3 NH 3 PbI 3-x Cl x , and 100 nm in CH 3 NH 3 PbI 3 , which in principle allows for the development of several solar cell architectures including perovskite-sensitized solar cells, planar heterojunction solar cells, and meso-and nanostructured solar cells. 17 Building on the dramatic improvement of solar cell performance using the solid hole conductor spiro-OMeTAD instead of a liquid electrolyte (spiro-OMeTAD stands for 2,2 0 -7,7 0 -tetrakis(N,N-di-p-methoxy-phenylamine)-9,9 0 -spirobifluorene), 18 the energy conversion efficiency of photovoltaics made from these intensely absorbing, visible-active semiconductors has risen from 3.8% to near 20% in only four years. 19,20 Photovoltaic performance depends critically on perovskite composition, crystallinity and morphology. 21À23 Higher perovskite film uniformity leads to lower recombination rates in planar heterojuction solar cells. 24,25 Film uniformity is affected by factors such as precursor composition, annealing temperature and, if applicable, solvent used during the vapor-assisted or spin coating deposition process. 6,24,26À32 Highly efficient mesostructured solar cells are produced by a twostep deposition process. 33À35 Vapor-assisted methods and additives provide the means * Address correspondence to jwp@iastate.edu, esmith1@iastate.edu, vela@iastate.edu.Received for review December 9, 2014 a...

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Section: Resultsmentioning

confidence: 99%

Shape Evolution and Single Particle Luminescence of Organometal Halide Perovskite Nanocrystals

et al. 2015

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“…[25][26][27][28][29] This is responsible for its bipolar conducting property and long carrier diffusion length (owing to absence of charge trapping centers). Because the M 3+ ion in A 2 M + M 3+ X VII 6 adopts the Sb 3+ /Bi 3+ that have the same electron configuration (ns 2 ) with Sn 2+ /Pb 2+ , it is reasonably conjectured that similar defect-tolerant feature might be to some extent at play here.…”

Section: Combinatory Materials Screening Of Potentially Highphotovoltmentioning

confidence: 99%

Design of Lead-Free Inorganic Halide Perovskites for Solar Cells via Cation-Transmutation

et al. 2017

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Hybrid organic-inorganic halide perovskites with the prototype material of CH 3 NH 3 PbI 3 have recently attracted intense interest as low-cost and high-performance photovoltaic absorbers. Despite the high power conversion efficiency exceeding 20% achieved by their solar cells, two key issues -the poor device stabilities associated with their intrinsic material instability and the toxicity due to water soluble Pb 2+ -need to be resolved before large-scale commercialization. Here, we address these issues by exploiting the strategy of cation-transmutation to design stable inorganic Pb-free halide perovskites for solar cells. The idea is to convert two divalent Pb 2+ ions into one monovalent M + and one trivalent M 3+ ions, forming a rich class of quaternary halides in double-perovskite structure. We find through first-principles calculations this class of materials have good phase stability against decomposition and wide-range tunable optoelectronic properties. With photovoltaic-functionality-directed materials screening, we identify eleven optimal materials with intrinsic thermodynamic stability, suitable band gaps, small carrier effective masses, and low excitons binding energies as promising candidates to replace Pb-based photovoltaic absorbers in perovskite solar cells. The chemical trends of phase stabilities and electronic properties are also established for this class of materials, offering useful guidance for the development of perovskite solar cells fabricated with them.

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“…In contrast, iodine-poor conditions obtained through the use of lead acetate as the precursor result in fewer defects and a longer charge diffusion length. [42] In a comparative study with other lead precursors, Aldibaja et al showed that films derived from lead acetate resulted in the most homogeneous perovskite films, and a photovoltaic performance comparable to the state-of-the-art. [43] Zhang et al further optimized the use of lead acetate as a precursor and showed that ultrasmooth and pinhole-free perovskite films could be obtained with this method.…”

Section: Crystallization From Lead-acetate Precursorsmentioning

confidence: 99%

Capturing the Sun: A Review of the Challenges and Perspectives of Perovskite Solar Cells

Petrus

Schlipf

Cheng

et al. 2017

Advanced Energy Materials

312

201

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following statement: These materials can be processed from solution and yet exhibit optoelectronic materials properties described in classic solid-state physics textbooks. This unprecedented combination has led to photovoltaic devices that can be processed at room temperature and achieve performance levels similar to industry giant polycrystalline silicon, from a starting point of 3.8% in 2009. [1][2][3][4] The first light-emitting electrochemical cells [5] and diodes [6][7][8] have also been introduced recently, leading to tunable light emission spectra and internal quantum efficiencies exceeding 15%.The road towards these achievements has been marked by a constant improvement of perovskite deposition techniques fueled by our increasing understanding of the crystallization processes. The choice of deposition technique, either from solution or vapor, and the composition and order in which precursor species are applied has a great influence on the crystallization kinetics. Here, one can distinguish one-step methods where the perovskite is formed from a precursor mixture dissolved in a common solution, and two-step methods where the inorganic compound is deposited first and transformed to the perovskite phase later by addition of the organic constituents. [9][10][11] Furthermore, many parameters during processing can have an effect on the crystallization mechanism and consequently on film morphology, such as the choice of solvents, concentrations and processing additives that are often not incorporated into the final product. [11][12][13] We discuss this aspect in Section 2, where we focus our attention on the most commonly employed solution-based techniques. Additionally, as for any new technology trying to displace an incumbent technology, higher efficiencies, lower costs, reproducibility, stability, and sustainability are paramount. In particular, reproducibility has been a major challenge in perovskite solar cells from the beginning: small variations in morphology, like crystal size, film roughness, and pinholes can have detrimental effects on photovoltaic performance. [14] On the other hand, current-voltage measurements often showed a hysteresis that is rarely seen in other photovoltaic technologies. [15] These topics are highlighted in Sections 3 and 4. Finally, in Section 5 we discuss the framework for market introduction, such as cost reduction by choosing low-cost charge transport layers, or how the lifetime of perovskite absorbers can be extended by the choice of materials composition.Hybrid metal halide perovskites have become one of the hottest topics in optoelectronic materials research in recent years. Not only have they surpassed everyone's expectations and achieved similar performance as tried and true polycrystalline silicon photovoltaic devices, but they are also finding applications in a variety of different fields, including lighting. The main advantages of hybrid metal halide perovskites are simple processability, compatible with large-scale solution processing such as roll-to-roll printing, a...

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Materials Processing Routes to Trap-Free Halide Perovskites

Cited by 694 publications

References 47 publications

Shape Evolution and Single Particle Luminescence of Organometal Halide Perovskite Nanocrystals

Shape Evolution and Single Particle Luminescence of Organometal Halide Perovskite Nanocrystals

Design of Lead-Free Inorganic Halide Perovskites for Solar Cells via Cation-Transmutation

Capturing the Sun: A Review of the Challenges and Perspectives of Perovskite Solar Cells

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