Coordination Chemistry Dictates the Structural Defects in Lead Halide Perovskites

Rahimnejad, Sara; Коваленко, А. В.; Forés, Sergio Martí; Aranda, Clara; Guerrero, Antonio

doi:10.1002/cphc.201600575

Cited by 172 publications

(245 citation statements)

References 20 publications

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“…The top view image (Figure 1a) of a device fabricated with a low proportion of DMSO (Ratio 0.5) clearly shows a fiber-like morphology typical from materials fabricated from pure DMF. 21,25,26 This result not only indicates that the proportion of DMSO is insufficient to generate the PbI 2 :MAI:Additive complex but also reveals the presence of uncovered electrode surface which will lead to the hole transport layer (HTL) to be in direct contact with the electron transport layer (ETL). As the DMSO proportion is increased to a DMSO:Pb ratio of 1.0 the complex is formed correctly as reported by Ahn et al 7 We observe a final morphology characterized by the presence of compact films with perovskite domains in the order of 100-500 nm ( Figure 1b).…”

Section: Resultsmentioning

confidence: 95%

“…7 Very importantly, the solution coordination chemistry of the lead atom with solvent and additives will dictate the chemical species that will be generated in the films. 25 In fact, several multiiodide plumbate ions chemical defects have been detected in films with proportions modulated by the processing conditions. For example, the effect of the solvent is key to stabilize the chemical defects and common solvents have been listed attending to the coordination ability towards PbI 2 : H 2 O>DMSO>DMF>GBL.…”

Section: Resultsmentioning

confidence: 99%

“…, PbI 6 4-and (Pb 2 I 4 ) n chains all responsible for the bands in the region of 500 nm. 21,29,25 Furthermore and to provide a complete picture of the absorbance response we also need to note that substrates partially covered by MAPbI 3 films are characterized by strong scattering >750 nm. This scattering observed when measurements are carried out using regular spectrophotometers, as opposed to optical microscopy of single crystals, leads to artifacts decreasing the intensity of bands in the range of 250-750 nm.…”

Section: Resultsmentioning

confidence: 99%

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Formation criteria of high efficiency perovskite solar cells under ambient conditions

Aranda

Cristobal

Shooshtari

et al. 2017

Sustainable Energy Fuels

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The field of lead halide perovskites for solar cell applications has recently reported impressive power conversion (PCE) above 22 % using complex mixed cation formulations. Very importantly, highest PCE have been obtained using totally dry environmental conditions increasing the processing costs (i.e. use of glovebox). In this work devices processed in air under different ambient conditions are prepared with PCE approaching 19 % for the simplest lead halide perovskite (MAPbI 3 , MA= Methyl ammonium). It is shown that the PbI 2 :MAI:additive complex needs to be generated in the correct stoichiometry (1:1:1) where additives are any highly polar molecule able to stabilize the complex (i.e. H 2 O or Dimethylsulphoxide (DMSO)). At high humidity conditions H 2 O is incorporated into the complex and only small concentrations of further additives are needed. Precursor formulations not adequately balanced for the humidity conditions lead to films with poor morphology as evidenced by SEM. These films show negative multiiodide plumbate chemical defects as observed by absorbance measurements. These chemical defects act as recombination centers reducing the photocurrent and Fill Factor in photovoltaic devices. In addition, it is shown the undesirable high conductivity of the perovskite hydrates (8x10 -1 Scm -1 ), up to seven orders of magnitude higher than the pure MAPbI 3 , indicating that the presence of hydrates may act as shunting pathways that can significantly reduce the open circuit potential.

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Section: Resultsmentioning

confidence: 95%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Formation criteria of high efficiency perovskite solar cells under ambient conditions

Aranda

Cristobal

Shooshtari

et al. 2017

Sustainable Energy Fuels

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“…However, the redshift of the PL peak was not observed, probably because the films were exposed to lower RH and less time than our MW sample or because the effect of humidity in thin films and MWs is different. Besides that, chemical and structural defects can acts as trap-assisted recombination centers for the photoexcited charge carriers [35, 37]. These trap states (i.e., vacancies, interstitials) are energy levels within the bandgap and can be deep and shallow traps [38].…”

Section: Resultsmentioning

confidence: 99%

Evolution of Photoluminescence, Raman, and Structure of CH3NH3PbI3 Perovskite Microwires Under Humidity Exposure

Segovia

Miao

et al. 2018

Nanoscale Res Lett

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Self-assembled organic-inorganic CH3NH3PbI3 perovskite microwires (MWs) upon humidity exposure along several weeks were investigated by photoluminescence (PL) spectroscopy, Raman spectroscopy, and X-ray diffraction (XRD). We show that, in addition to the common perovskite decomposition into PbI2 and the formation of a hydrated phase, humidity induced a gradual PL redshift at the initial weeks that is stabilized for longer exposure (~ 21 nm over the degradation process) and an intensity enhancement. Original perovskite Raman band and XRD reflections slightly shifted upon humidity, indicating defects formation and structure distortion of the MWs crystal lattice. By correlating the PL, Raman, and XRD results, it is believed that the redshift of the MWs PL emission was originated from the structural disorder caused by the incorporation of H2O molecules in the crystal lattice and radiative recombination through moisture-induced subgap trap states. Our study provides insights into the optical and structural response of organic-inorganic perovskite materials upon humidity exposure.Electronic supplementary materialThe online version of this article (10.1186/s11671-018-2470-0) contains supplementary material, which is available to authorized users.

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“…[54] As a polar solvent, water could coordinate the lead atom, competing with the halides to occupy the octahedral sites of the characteristic crystalline perovskite structure MA(FA)PbX 3 . [56] Regarding this coordination chemistry study, an antisolvent method to fabricate high PCE PSCs under different humidity conditions was reported by our group in 2017. [56] Regarding this coordination chemistry study, an antisolvent method to fabricate high PCE PSCs under different humidity conditions was reported by our group in 2017.…”

Section: Universal Methods Of Fabrication At Room Conditionsmentioning

confidence: 96%

Crystalline Clear or Not: Beneficial and Harmful Effects of Water in Perovskite Solar Cells

2019

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Clarification of how water affects the photovoltaic performance of perovskite solar cells is one of the major challenges to successfully develop a large-scale low-cost fabrication process. Many authors have reported beneficial effects of moisture during the fabrication of perovskite solar cells (PSCs), such as enhanced crystallinity, photoluminescence and photovoltage. However, the highest power conversion efficiency reported until this date was obtained under completely dry atmosphere conditions, avoiding the presence of water during perovskite formulation and preserving the damage caused by moisture exposure with encapsulation techniques. This apparent contradiction makes patent the necessity of an extensive clarification to establish the conditions in which water represents a beneficial or harmful factor in the development of high efficiency and stable perovskite devices. In this review, we summarized the effects of water, both as an additive into the perovskite formulation as an additive and as moisture exposure during fabrication. We discuss in depth the structural and chemical effects, analysing also the photovoltaic consequences during operation conditions. As a final input, we remark a useful method to perform high efficiency PSCs under different lab ambient conditions and highlight the latest advances in hydrophobic devices and encapsulation techniques.

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Coordination Chemistry Dictates the Structural Defects in Lead Halide Perovskites

Cited by 172 publications

References 20 publications

Formation criteria of high efficiency perovskite solar cells under ambient conditions

Formation criteria of high efficiency perovskite solar cells under ambient conditions

Evolution of Photoluminescence, Raman, and Structure of CH3NH3PbI3 Perovskite Microwires Under Humidity Exposure

Crystalline Clear or Not: Beneficial and Harmful Effects of Water in Perovskite Solar Cells

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