Charge carrier dynamics of methylammonium lead iodide: from PbI<sub>2</sub>-rich to low-dimensional broadly emitting perovskites

Klein, Johannes R.; Flender, Oliver; Scholz, Mirko; Oum, Kawon; Lenzer, Thomas

doi:10.1039/c5cp07167d

Cited by 50 publications

(94 citation statements)

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“…15 mg·ml −1 and 20 mg·ml −1 of MAI), the size of perovskite nanocube further decreased (Figure S1h,k) and small PbI 2 peak was shown again (Figure S1g,j), which was likely due to the decomposition of MAPbI 3 29. Especially, at the highest concentration of MAI (20 mg·ml −1 ), a peak around 2 θ = 11.5°, related to the low-dimensional perovskite structures (LDPs) such as 0D (quantum dot), 1D (chain) and 2D (sheet) structures, known to be found in MAI-rich film3031, was generated, and the performances eventually decreased to 6.8% PCE ( V oc = 0.89 V, J sc = 11.4 mA·cm −2 and FF = 0.66; average values of forward and reverse scan). The performance variation of the printed PSCs according to the MAI concentration is summarized in Figure S3.…”

Section: Resultsmentioning

confidence: 91%

Investigation into the Advantages of Pure Perovskite Film without PbI2 for High Performance Solar Cell

Kwon

Hasan

Yin

et al. 2016

Sci Rep

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In CH3NH3PbI3-based high efficiency perovskite solar cells (PSCs), tiny amount of PbI2 impurity was often found with the perovskite crystal. However, for two-step solution process-based perovskite films, most of findings have been based on the films having different morphologies between with and without PbI2. This was mainly due to the inferior morphology of pure perovskite film without PbI2, inevitably produced when the remaining PbI2 forced to be converted to perovskite, so advantages of pure perovskite photoactive layer without PbI2 impurity have been overlooked. In this work, we designed a printing-based two-step process, which could not only generate pure perovskite crystal without PbI2, but also provide uniform and full surface coverage perovskite film, of which nanoscale morphology was comparable to that prepared by conventional two-step solution process having residual PbI2. Our results showed that, in two-step solution process-based PSC, pure perovskite had better photon absorption and longer carrier lifetime, leading to superior photocurrent generation with higher power conversion efficiency. Furthermore, this process was further applicable to prepare mixed phase pure perovskite crystal without PbI2 impurity, and we showed that the additional merits such as extended absorption to longer wavelength, increased carrier lifetime and reduced carrier recombination could be secured.

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Section: Resultsmentioning

confidence: 91%

Investigation into the Advantages of Pure Perovskite Film without PbI2 for High Performance Solar Cell

Kwon

Hasan

Yin

et al. 2016

Sci Rep

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“…Ultrafast UV-Vis-NIR transient absorption spectra were recorded at 920 Hz repetition frequency on three different setups employing the PSCP technique. 13,14,[24][25][26][27] In the first setup, 27,28 a multifilament Vis-NIR supercontinuum covering the wavelength range 500-920 nm was generated in a translating 2 mm thick CaF 2 plate using a noncollinearly phase-matched optical parametric amplifier (NOPA) running at 630 nm (12 mJ pulse À1 ). The NOPA was driven by a regeneratively amplified titanium:sapphire system (Spectra-Physics Hurricane, 780 nm, 90 fs, 1 mJ pulse À1 ).…”

Section: Pump -Supercontinuum Probe (Pscp) Spectroscopymentioning

confidence: 99%

Excited-state relaxation of the solar cell dye D49 in organic solvents and on mesoporous Al₂O₃ and TiO₂ thin films

Flender

Scholz

Klein

et al. 2016

Phys. Chem. Chem. Phys.

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We present an ultrafast UV-Vis-NIR transient absorption study of the donor-acceptor solar-cell dye D49 in diisopropyl ether, THF and acetonitrile, as well as on mesoporous AlO and TiO thin films. Photoexcitation at 505 nm initially populates the first electronically excited state of the dye having significant intramolecular charge transfer character ("S/ICT"). On AlO and in the three organic solvents, the dynamics are fully explained in terms of S/ICT stabilisation (by reorientation of adjacent solvent or D49 molecules and collisional cooling), intramolecular vibrational redistribution and S/ICT → S electronic decay. A substantial decrease of the S/ICT lifetime is observed with increasing polarity of the surrounding medium suggesting an acceleration of internal conversion. In agreement with these results, the addition of the nonpolar co-adsorbent deoxycholic acid (DCA) to the AlO surface leads to a substantial increase of the S/ICT lifetime. DCA spacers reduce the local polarity around the dye molecules, thus interrupting D49 "self-solvation". These results are in contrast to a recent experimental study for the indoline dye D131 on AlO, where charge transfer from electronically excited D131 to adjacent dye molecules was proposed (Cappel et al., Sci. Rep., 2016, 6, 21276). We do not see evidence for charge transfer processes between D49 molecules and also not for electron injection from D49 into AlO trap states. Charge separation is only observed for D49 bound to TiO thin films, with efficient injection of electrons into the conduction band of the semiconductor via formation of a [D49˙e] complex and a transient Stark effect signalling the formation of mobile electrons upon dissociation of the complex.

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“…Recent studies have shown that the remnant PbI 2 on the perovskite films passivate the defects in the grain boundaries thereby enhancing the photoconversion efficiency (PCE) of the lead‐iodide‐based hybrid perovskite solar cells . Varying the initial mole fractions of PbI 2 in methylammonium lead iodide perovskites have shown to alter the steady state absorption and the ultrafast carrier dynamics of the perovskite material . Furthermore, PbI 2 possessing the energy bandgap of 2.35 eV is a direct‐bandgap material showing high photon–electron conversion efficiency, thereby favoring its applications in efficient optoelectronic devices.…”

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Solution‐Processed Lead Iodide for Ultrafast All‐Optical Switching of Terahertz Photonic Devices

et al. 2019

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technological relevance, currently there is a huge quest for ultrafast switchable/tunable metasurfaces that possess low threshold switching and easy fabrication techniques. Recent progress and new approaches on tunable metasurfaces [12] based on spincoating and thermal evaporation [13] of semiconductors on metasurfaces have given promising pathways for realizing ultrasensitive, low energy ultrafast devices. Among them solution-processed organic-inorganic perovskites have shown promising pathways in realizing tunable metasurfaces with their easy fabrication techniques and excellent photoresponsive properties. [14][15][16] Further, solution processed perovskites have shown to exhibit plasmonic behavior and have emerged as novel platform for realizing tunable metasurfaces at optical frequencies. [17,18] In the recent studies, it was shown that by photodoping the solution-processed methyl ammonium lead iodide (CH 3 NH 3 PbI 3 ) perovskite materials spin coated on the metasurface aids in ultrasensitive reconfiguration of its resonances on rigid and flexible substrates at THz frequencies. [19,20] However, the switching speed in these hybrid devices is limited to nanoseconds that is dictated by the recombination lifetimes of the photoexcited free carriers in the perovskite thin films.The other class of solution processed compounds such as metal-halides show promising features to enhance the optoelectronic properties of perovskites by modifying their absorbance and photocarrier lifetimes. Such compounds with more simpler preparation techniques would provide an ideal platform for photoswitching applications on rigid as well as flexible photonics platforms. Among the metal-halides, the solutionprocessed lead iodide (PbI 2 ) precursor was found to play a significant role than envisaged in dictating the performance and quality of the perovskite-based photovoltaic devices. Concerned with its toxicity, many attempts are being carried out to replace the lead-based legends in perovskites, nevertheless, the rich chemical and photophysical properties of lead-iodide in enhancing the photovoltaic [21] and light-emitting properties [14] of hybrid perovskites has been phenomenal compared to other metal-halide compounds. Recent studies have shown that the remnant PbI 2 on the perovskite films passivate the defects in the grain boundaries thereby enhancing the photoconversion efficiency (PCE) of the lead-iodide-based hybrid perovskite solar cells. [22][23][24] Varying the initial mole fractions of PbI 2 in Solution-processed lead iodide (PbI 2 ) governs the charge transport characteristics in the hybrid metal halide perovskites. Besides being a precursor in enhancing the performance of perovskite solar cells, PbI 2 alone offers remarkable optical and ultrasensitive photoresponsive properties that remain largely unexplored. Here, the photophysics and the ultrafast carrier dynamics of the solution processed PbI 2 thin film is probed experimentally. A PbI 2 integrated metamaterial photonic device with switchable picosecond time response at...

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Charge carrier dynamics of methylammonium lead iodide: from PbI₂-rich to low-dimensional broadly emitting perovskites

Cited by 50 publications

References 44 publications

Investigation into the Advantages of Pure Perovskite Film without PbI2 for High Performance Solar Cell

Investigation into the Advantages of Pure Perovskite Film without PbI2 for High Performance Solar Cell

Excited-state relaxation of the solar cell dye D49 in organic solvents and on mesoporous Al₂O₃ and TiO₂ thin films

Solution‐Processed Lead Iodide for Ultrafast All‐Optical Switching of Terahertz Photonic Devices

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Charge carrier dynamics of methylammonium lead iodide: from PbI2-rich to low-dimensional broadly emitting perovskites

Cited by 50 publications

References 44 publications

Investigation into the Advantages of Pure Perovskite Film without PbI2 for High Performance Solar Cell

Investigation into the Advantages of Pure Perovskite Film without PbI2 for High Performance Solar Cell

Excited-state relaxation of the solar cell dye D49 in organic solvents and on mesoporous Al2O3 and TiO2 thin films

Solution‐Processed Lead Iodide for Ultrafast All‐Optical Switching of Terahertz Photonic Devices

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Charge carrier dynamics of methylammonium lead iodide: from PbI₂-rich to low-dimensional broadly emitting perovskites

Excited-state relaxation of the solar cell dye D49 in organic solvents and on mesoporous Al₂O₃ and TiO₂ thin films