Two-step growth of CsPbI<sub>3−x</sub>Br<sub>x</sub> films employing dynamic CsBr treatment: toward all-inorganic perovskite photovoltaics with enhanced stability

Parida, Bhaskar; Ryu, Jun; Yoon, Suk-Young; Lee, Seojun; Seo, Yejin; Cho, Jung Sang; Kang, Dong‐Won

doi:10.1039/c9ta05948b

Cited by 47 publications

(36 citation statements)

References 44 publications

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“…When including the SOC effect in PBE-GGA and HSE [18] for CsPbI 3 , ref. [41] for CsPbI 3−x Br x (x = 0.66), ref. [38,39] for CsPbIBr 2 and ref.…”

Section: Electronic and Optical Propertiesmentioning

confidence: 99%

“…It should be noted that during the anion exchange their solid solutions CsPb(Br x I 1-x ) 3 are not excluded to form, especially in thicker film. Rather, to avoid the phase degradation of CsPbI 3 under ambient conditions, many researchers preferred to develop bromide-based PSCs such as CsPbBr 3 (efficiency, 8.8%) [33,34,35], CsPbIBr 2 (9.8%) [36,37,38,39], CsPbI 2 Br (16.1%) [40] and CsPb(Br x I 1-x ) 3 (x = 0.66, 14.1%) [41,42,43,44]. In spite of such intensive experimental studies, theoretical works are yet absent and thus a persuasive explanation for halide anion exchange is not provided.…”

Section: Introductionmentioning

confidence: 99%

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First-principles study on material properties and stability of inorganic halide perovskite solid solutions CsPb(I1−xBrx)3

Yu¹,

Ko²,

Hwang³

et al. 2020

Phys. Rev. Materials

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All-inorganic halide perovskites have attracted a great interest as a promising light harvester of perovskite solar cells due to their enhanced chemical stability. In this work we investigate the material properties of solid solutions CsPb(I 1−x Br x ) 3 in cubic phase by applying the virtual crystal approximation approach within a density functional theory framework. First we check the validity of constructed pseudopotentials of the virtual atoms (X = I 1−x Br x ) by verifying that the lattice constants follow the linear function of mixing ratio. We then suggest an idea of using the hybrid HSE functional with linear increasing value of exact exchange term as increasing the Br content x, which produces the band gaps of CsPbX 3 in good agreement with the available experimental data. The calculated light absorption coefficients and reflectivity show the systematic varying tendency to the Br content. We calculate the phonon dispersions of CsPbX 3 , CsX and PbX 2 as slightly changing their volumes, revealing the phase instability of CsPbX 3 and calculating the thermodynamic potential function differences. By projecting Gibbs free energy differences onto the plane of ∆G = 0, we determine the P − T diagram for CsPbX 3 to be stable against the chemical decomposition, highlighting that the area of being stable extends gradually as the Br content increases.

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“…When including the SOC effect in PBE-GGA and HSE [18] for CsPbI 3 , ref. [41] for CsPbI 3−x Br x (x = 0.66), ref. [38,39] for CsPbIBr 2 and ref.…”

Section: Electronic and Optical Propertiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

First-principles study on material properties and stability of inorganic halide perovskite solid solutions CsPb(I1−xBrx)3

Yu¹,

Ko²,

Hwang³

et al. 2020

Phys. Rev. Materials

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“…One of the most commonly studied 3D perovskites, MAPbI 3 , degrades under thermal stress due to the highly volatile MA+ ion [ 1 ]. Another thoroughly studied 3D perovskite, CsPbI 3 , demonstrates excellent thermal stability; however, it undergoes a phase change at room temperature to a form a large bandgap that is insufficient for absorbing UV radiation [ 4 ]. FAPbI 3 , on the other hand, also suffers from phase instability, as indicated by the presence of the yellow phase in the perovskite at room temperature [ 5 ].…”

Section: Introductionmentioning

confidence: 99%

“…Several studies have been dedicated to analyzing the effect of mixed cations and halides to enhance PSCs’ stability and efficiency. Mixed cation perovskite is a unique way to benefit from the combined distinctive features of single cations: improved bandgap of perovskites with FA+ [ 9 ], impressive thermal stability with Cs+ [ 4 ], and high charge carrier mobility and long diffusion length with MA+ [ 5 , 10 , 11 ]. Incorporating MA cations with FA restricts the transition to the yellow non-perovskite phase by stabilizing the perovskite phase and enhancing the perovskite’s thermal and structural stability compared to the pure MA+ and FA+ cation 3D perovskite [ 12 , 13 ].…”

Section: Introductionmentioning

confidence: 99%

Long-Term Stability Analysis of 3D and 2D/3D Hybrid Perovskite Solar Cells Using Electrochemical Impedance Spectroscopy

et al. 2020

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Despite the remarkable progress in perovskite solar cells (PSCs), their instability and rapid degradation over time still restrict their commercialization. A 2D capping layer has been proved to overcome the stability issues; however, an in-depth understanding of the complex degradation processes over a prolonged time at PSC interfaces is crucial for improving their stability. In the current work, we investigated the stability of a triple cation 3D ([(FA0.83MA0.17)Cs0.05]Pb(I0.83Br0.17)3) and 2D/3D PSC fabricated by a layer-by-layer deposition technique (PEAI-based 2D layer over triple cation 3D perovskite) using a state-of-art characterization technique: electrochemical impedance spectroscopy (EIS). A long-term stability test over 24 months was performed on the 3D and 2D/3D PSCs with an initial PCE of 18.87% and 20.21%, respectively, to suggest a more practical scenario. The current-voltage (J-V) and EIS results showed degradation in both the solar cell types; however, a slower degradation rate was observed in 2D/3D PSCs. Finally, the quantitative analysis of the key EIS parameters affected by the degradation in 3D and 2D/3D PSCs were discussed.

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“…[ 29 ] The highest PCE for dopant‐free P3HT‐based all‐inorganic PSCs is just 14.08% although the devices show much improved ambient stability. [ 30 ] Recently, Seo and co‐workers reported that the wide‐bandgap interlayer could increase the open‐circuit voltage ( V oc ) and thus PCE for organic–inorganic hybrid PSCs. [ 31 ] Based on these facts, developing suitable methods to reduce the recombination in perovskite layer and suitable interlayer to alleviate the recombination at perovskite/P3HT interface would be effective to achieve high‐efficiency CsPbI 2 Br PSCs with dopant‐free P3HT HTM.…”

Section: Figurementioning

confidence: 99%

High‐Efficiency CsPbI₂Br Perovskite Solar Cells with Dopant‐Free Poly(3‐hexylthiophene) Hole Transporting Layers

Liu

Qiu

et al. 2020

Advanced Energy Materials

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In contrast, thermodynamically stable orthorhombic CsPbI 3 (δ-CsPbI 3 , yellow phase) has a bandgap of about 2.82 eV, which is not suitable for photovoltaic application. This phase transition issue calls for the efforts on developing other all-inorganic perovskite materials. By replacing halide to increase Gold-Schmidt tolerance factor, CsPbI 2 Br with more stable lattice structure is emerging as an alternative for photovoltaics. [12][13][14][15][16][17] The challenges remain in the fabrication of high-quality CsPbI 2 Br film and thus high-efficiency solar cells.Several strategies have been attempted to improve the performance of CsPbI 2 Br perovskite solar cells (PSCs). For example, the CsPbI 2 Br quantum dots were synthesized as absorber layer to deliver a V oc of 1.32 V and a PCE of 12.02%. [18] The hotcast method was applied to increase the PCE of CsPbI 2 Br perovskite solar cells to 14.81%. [16] A significant PCE of 16.07% was achieved by improving the crystallization of CsPbI 2 Br film via isopropanol-assisted antisolvent processing. [4] More recently, the PCE of CsPbI 2 Br PSCs has been pushed to 16.58% by regulating the grain growth and perovskite surface. [19] Although the efficiency is still lower than those of hybrid organic-inorganic PSCs and even CsPbI 3 devices, the much less phase transition issue and sensitivity to moisture for CsPbI 2 Br compared with CsPbI 3 make it promising for the investigation of challenges and solutions in all-inorganic perovskite photovoltaic devices.Up to now, high-efficiency all-inorganic PSCs are usually based on doped hole transporting materials (HTMs) such as sprio-OMeTAD and PTAA with additives of lithium salts or cobalt salts and 4-tert-butyl pyridine (TBP). [20,21] It is well known that hygroscopic Li salts and TBP could adsorb moisture, leading to serious device degradation. [22,23] To address this issue, hydrophobic materials (such as polystyrene and PVDF) are introduced as interlayers to improve the moisture resistance of devices. [24,25] Poly(3-hexylthiophene) (P3HT) is another alternative additive-free HTM in view of its excellent hole mobility and low cost. [26][27][28] Unfortunately, due to severe nonradiative recombination at the perovskite/P3HT interface, the P3HTbased PSCs still exhibit low efficiency with low open-circuit voltage. [29] The highest PCE for dopant-free P3HT-based allinorganic PSCs is just 14.08% although the devices show much CsPbI 2 Br is emerging as a promising all-inorganic material for perovskite solar cells (PSCs) due to its more stable lattice structure and moisture resistance compared to CsPbI 3 , although its device performance is still much behind this counterpart. Herein, a preannealing process is developed and systematically investigated to achieve high-quality CsPbI 2 Br films by regulating the nucleation and crystallization of perovskite. The preannealing temperature and time are specifically optimized for a dopant-free poly(3hexylthiophene) (P3HT)-based device to target dopant-induced drastic performance degradation for spiro...

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Two-step growth of CsPbI_3−xBr_x films employing dynamic CsBr treatment: toward all-inorganic perovskite photovoltaics with enhanced stability

Abstract: The dynamic CsBr treatment on α-CsPbI3 significantly improves the power conversion efficiency, reproducibility, and stability of all-inorganic CsPbI3−xBrx perovskite solar cells.

Cited by 47 publications

References 44 publications

First-principles study on material properties and stability of inorganic halide perovskite solid solutions CsPb(I1−xBrx)3

First-principles study on material properties and stability of inorganic halide perovskite solid solutions CsPb(I1−xBrx)3

Long-Term Stability Analysis of 3D and 2D/3D Hybrid Perovskite Solar Cells Using Electrochemical Impedance Spectroscopy

High‐Efficiency CsPbI₂Br Perovskite Solar Cells with Dopant‐Free Poly(3‐hexylthiophene) Hole Transporting Layers

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Two-step growth of CsPbI3−xBrx films employing dynamic CsBr treatment: toward all-inorganic perovskite photovoltaics with enhanced stability

Abstract: The dynamic CsBr treatment on α-CsPbI3 significantly improves the power conversion efficiency, reproducibility, and stability of all-inorganic CsPbI3−xBrx perovskite solar cells.

Cited by 47 publications

References 44 publications

First-principles study on material properties and stability of inorganic halide perovskite solid solutions CsPb(I1−xBrx)3

First-principles study on material properties and stability of inorganic halide perovskite solid solutions CsPb(I1−xBrx)3

Long-Term Stability Analysis of 3D and 2D/3D Hybrid Perovskite Solar Cells Using Electrochemical Impedance Spectroscopy

High‐Efficiency CsPbI2Br Perovskite Solar Cells with Dopant‐Free Poly(3‐hexylthiophene) Hole Transporting Layers

Contact Info

Product

Resources

About

Two-step growth of CsPbI_3−xBr_x films employing dynamic CsBr treatment: toward all-inorganic perovskite photovoltaics with enhanced stability

High‐Efficiency CsPbI₂Br Perovskite Solar Cells with Dopant‐Free Poly(3‐hexylthiophene) Hole Transporting Layers