On the True Band Gap of the (CH3NH3)2Pb(SCN)2I2 Hybrid Perovskite: An Interesting Solar‐Cell Material

Penagos, Josue I. Clavijo; Romero, E.; Gordillo, G.; Hoyos, John Michael Correa; Reinoso, M. A.

doi:10.1002/pssr.201700376

Cited by 11 publications

(7 citation statements)

References 21 publications

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“…From extrapolation of the linear part of the Tauc plot [33,34], the bandgap of (CH 3 NH 3 ) 2 Pb(SCN) 2 I 2 is estimated as 2.04 eV. This bandgap assignment of (CH 3 NH 3 ) 2 Pb(SCN) 2 I 2 is consistent with the reported values in the literature [21,26,30,33,35]. This bandgap is smaller than that of other typical single-layered Pb-I perovskites which is likely due to the reduced confinement of inorganic sheets that are induced by the shorter spacing and octahedral tilting in the inorganic sheets [36].…”

Section: Resultssupporting

confidence: 87%

Impact of Dimensionality on Optoelectronic Properties of Hybrid Perovskites

Ware

Wright

Davita³

et al. 2021

International Journal of Photoenergy

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Organometal halides are promising materials for photovoltaic applications, offering tunable electronic levels, excellent charge transport, and simplicity of thin-film device fabrication. Two-dimensional (2D) perovskites have emerged as promising candidates over three-dimensional (3D) ones due to their interesting optical and electrical properties. However, maximizing the power conversion efficiency is a critical issue to improve the performance of these solar cells. In this work, we studied the photophysics of a two-dimensional (2D) perovskite (CH3NH3)2Pb(SCN)2I2 thin film using steady-state and time-resolved absorption and emission spectroscopy and compared it with the three-dimensional (3D) counterpart CH3NH3PbI3. We observed a higher bandgap and faster charge recombination in (CH3NH3)2Pb(SCN)2I2 compared to CH3NH3PbI3. This work provides an improved understanding of fundamental photophysical processes in perovskite structures and provides the guideline for the design, synthesis, and fabrication of solar cells.

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Section: Resultssupporting

confidence: 87%

Impact of Dimensionality on Optoelectronic Properties of Hybrid Perovskites

Ware

Wright

Davita³

et al. 2021

International Journal of Photoenergy

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“…Several reports have described the incorporation of SCN – as an additive in MAPbI 3 PSC devices, demonstrating improved stability and decreased hysteresis. Pseudohalide SCN – improves moisture tolerance and device stability, decreases trap-assisted recombination, and enhances charge-carrier lifetimes. ,,,− For Pb perovskites, the incorporation of thiocyanates by more than 15% into the lattice, however, leads to the formation of a two-dimensional (2D) structure or mixed phases of MAPbI 3 and MAPbI 2 (SCN), with MAPbI 3 being the dominant phase. , Pure 2D phase MA 2 Pb(SCN) 2 I 2 exhibits a poor device performance with PCE consistently less than 3.5%. , In contrast, when used as an additive, thiocyanate-doped Sn perovskite films showed an improved morphology and crystallinity. , Considering the size difference between Pb 2+ and Sn 2+ , we expect the incorporation of SCN – ions into the crystal lattice of a tin perovskite to result in a three dimensional (3D) structure and thereby to improve the device performance and stability with suppressed recombination and enhanced tolerance to moisture.…”

Section: Introductionmentioning

confidence: 99%

“…13,14,17,19−21 For Pb perovskites, the incorporation of thiocyanates by more than 15% into the lattice, however, leads to the formation of a twodimensional (2D) structure or mixed phases of MAPbI 3 and MAPbI 2 (SCN), with MAPbI 3 being the dominant phase. 22,23 Pure 2D phase MA 2 Pb(SCN) 2 I 2 exhibits a poor device performance with PCE consistently less than 3.5%. 13,20 In contrast, when used as an additive, thiocyanate-doped Sn perovskite films showed an improved morphology and crystallinity.…”

Section: ■ Introductionmentioning

confidence: 99%

Development of Hybrid Pseudohalide Tin Perovskites for Highly Stable Carbon-Electrode Solar Cells

Rameez

Lin

Raghunath

et al. 2020

ACS Appl. Mater. Interfaces

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Tin-based perovskites degrade rapidly upon interaction with water and oxygen in air because Sn–I bonds are weak. To address this issue, we developed novel tin perovskites, FASnI(3–x)(SCN) x (x = 0, 1, 2, or 3), by employing a pseudohalide, thiocyanate (SCN–), as a replacement for halides and as an inhibitor to suppress the Sn2+/Sn4+ oxidation. The structural and electronic properties of pseudohalide tin perovskites in this series were explored with quantum-chemical calculations by employing the plane-wave density functional theory (DFT) method; the corresponding results are consistent with the experimental results. Carbon-based perovskite devices fabricated with tin perovskite FASnI(SCN)2 showed about a threefold enhancement of the device efficiency (2.4%) relative to that of the best FASnI3-based device (0.9%), which we attribute to the improved suppression of the formation of Sn4+, retarded charge recombination, enhanced hydrophobicity, and stronger interactions between Sn and thiocyanate for FASnI(SCN)2 than those for FASnI3. After the incorporation of phenylethyleneammonium iodide (PEAI, 10%) and ethylenediammonium diiodide (EDAI2, 5%) as coadditives, the FASnI(SCN)2 device gave the best photovoltaic performance with J SC = 20.17 mA cm–2, V OC = 322 mV, fill factor (FF) = 0.574, and overall efficiency of power conversion PCE = 3.7%. Moreover, these pseudohalide-containing devices display negligible photocurrent–voltage hysteresis and great stability in ambient air conditions.

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“…[54] Copyright 2019, American Chemical Society. [73] The diffuse reflectance spectra (DRS) measurement and DFT calculation demonstrated that the MA 2 Pb(SCN) 2 I 2 perovskite have a bandgap of around 2.138 eV, which is favorable for the application on tandem and multi-junction solar cells. It is noted that the VBM is located at the T point in the Brillouin zone which does not coincide with the CBM, leading to an indirect bandgap material.…”

Section: Band Structurementioning

confidence: 99%

Pseudo‐Halide Perovskite Solar Cells

Lin

Loganathan

Raifuku

et al. 2021

Advanced Energy Materials

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class of solar absorber material. These halide perovskite materials have been known since 1970s, and their optical and electrical properties had been investigated by several groups. [1][2][3][4][5][6] Toward their application in solar cells, Kojima et al. first employed CH 3 NH 3 PbI 3 and CH 3 NH 3 PbBr 3 as the light absorber using dye-sensitized solar cell configuration. [7] M. Grätzel and co-workers reported the first all-solid-state perovskite-based mesoscopic solar cells. [8] These class of perovskites material offers unique opto-electronic traits namely ambipolar charge transport, high absorption coefficient, and long electron/hole diffusion length, making them highly desired for PV application. Moreover, the ease of synthesis and low temperature crystallization makes them a good choice for low cost PV devices with high efficiencies. Being aware of these aforementioned remarkable optoelectronic properties and solution processability of halide perovskites, perovskite solar cells (PSCs) have attracted immense research attention worldwide. [9][10][11][12][13][14] They demonstrate a certified PCE of 25.5%, which is higher than that of organic solar cells and most of inorganic solar cells such as multi-crystalline silicon and copper indium gallium diselenide based solar cells. [15] In addition to their application in solar cells, owing to their intrinsic properties the halide perovskites have been employed in a wide range of optoelectronic devices, such as light-emitting diode (LED), lasers, photodetectors, and Perovskite solar cells (PSCs) have achieved certified power conversion efficiency (PCE) over 25%. Though their high PCE can be achieved by optimizing absorber layer and device interfaces, the intrinsic instability of perovskite materials is still a key issue to be resolved. Mixed-halide perovskites using multiple halogen constituents have been proved to improve robustness; however, the anion at the X site in the ABX 3 formula is not limited to halogens. Other negative monovalent ions with similar properties to halogens, such as pseudo-halogens, have the opportunity to form perovskites with ABX 3 stoichiometry. Recently, thiocyanates and formates have been utilized to synthesize stable perovskite materials. This review presents the evolution of pseudo-halide perovskite solar cells in the past few years. The intrinsic properties, their effects on crystal structure, and bandgap engineering of the pseudo-halide perovskites are summarized. Various thiocyanate compounds applied in the fabrication of perovskite solar cells are discussed. The fabrication process, film formation mechanism, and crystallinity of pseudo-halide perovskites are elucidated to understand their effects on the photovoltaic performance and device stability. Other applications of pseudo-halide perovskites are summarized in the final section. Lastly, this review concludes with suggestions and outlooks for further research directions.

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On the True Band Gap of the (CH₃NH₃)₂Pb(SCN)₂I₂ Hybrid Perovskite: An Interesting Solar‐Cell Material

Cited by 11 publications

References 21 publications

Impact of Dimensionality on Optoelectronic Properties of Hybrid Perovskites

Impact of Dimensionality on Optoelectronic Properties of Hybrid Perovskites

Development of Hybrid Pseudohalide Tin Perovskites for Highly Stable Carbon-Electrode Solar Cells

Pseudo‐Halide Perovskite Solar Cells

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