Microscopic Degradation in Formamidinium-Cesium Lead Iodide Perovskite Solar Cells under Operational Stressors

Li, Nengxu; Luo, Yanqi; Chen, Zehua; Niu, Xiuxiu; Zhang, Xiao; Lu, Jiuzhou; Kumar, Rishi E.; Jiang, Junke; Liu, Huifen; Guo, Xiao; Lai, Barry; Brocks, G.; Chen, Qi; Tao, Shuxia; Fenning, David P.; Zhou, Huanping

doi:10.1016/j.joule.2020.06.005

Cited by 200 publications

(198 citation statements)

References 65 publications

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“…In order to improve the thermal stability of the device, a small quantity of poly[bis(4‐phenyl)(2,4,6‐trimethylphenyl)amine] was added into Spiro‐OMeTAD layer according to the literature. [ 56 ] As shown in Figure 7c,d. it is obvious that the hybrid PSCs with DFPDA additive exhibit more stable performance than the control devices.…”

Section: Resultsmentioning

confidence: 86%

Multifunctional Enhancement for Highly Stable and Efficient Perovskite Solar Cells

Cai

Cui

Chen

et al. 2020

Adv Funct Materials

322

273

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With a certified efficiency as high as 25.2%, perovskite has taken the crown as the highest efficiency thin film solar cell material. Unfortunately, serious instability issues must be resolved before perovskite solar cells (PSCs) are commercialized. Aided by theoretical calculation, an appropriate multifunctional molecule, 2,2‐difluoropropanediamide (DFPDA), is selected to ameliorate all the instability issues. Specifically, the carbonyl groups in DFPDA form chemical bonds with Pb2+ and passivate under‐coordinated Pb2+ defects. Consequently, the perovskite crystallization rate is reduced and high‐quality films are produced with fewer defects. The amino groups not only bind with iodide to suppress ion migration but also increase the electron density on the carbonyl groups to further enhance their passivation effect. Furthermore, the fluorine groups in DFPDA form both an effective barrier on the perovskite to improve its moisture stability and a bridge between the perovskite and HTL for effective charge transport. In addition, they show an effective doping effect in the HTL to improve its carrier mobility. With the help of the combined effects of these groups in DFPDA, the PSCs with DFPDA additive achieve a champion efficiency of 22.21% and a substantially improved stability against moisture, heat, and light.

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Section: Resultsmentioning

confidence: 86%

Multifunctional Enhancement for Highly Stable and Efficient Perovskite Solar Cells

Cai

Cui

Chen

et al. 2020

Adv Funct Materials

322

273

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“…These results can be ascribed to the improved stability of the perovskite black phase and improved morphology, which assure reduced or suppressed ion migration under operational conditions, induced by light or the high temperatures. [54,64] In order to corroborate the strong and robust impact of the PbS NPLs on device stability, the same devices were fabricated also under ambient conditions (in air, 25 °C and 50-55% RH). While the environmental surroundings usually play a dramatic role in achieving reproducible device performances and properties, [65] the solar cell parameters of devices fabricated under ambient conditions, see Figure 7 and Figure S10, Supporting Information, show a similar trend as the ones fabricated under inert conditions, [66] and a record PCE of ≈17% is achieved with the addition of PbS NPLs with 0.5 mg mL −1 concentration.…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Preferred Growth Direction by PbS Nanoplatelets Preserves Perovskite Infrared Light Harvesting for Stable, Reproducible, and Efficient Solar Cells

Sánchez-Godoy

Erazo

Gualdrón‐Reyes

et al. 2020

Advanced Energy Materials

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Due to its impressive properties such as a high absorption coefficient, long diffusion length and low exciton dissociation energy, [2] the perovskite has been exploited in several applications, among them light amplifiers and lasers, [3-,5] light emitting diodes (LEDs), [6-8] and photovoltaic devices. [9,10] The halide perovskite structure, ABX 3 [11] allows multiple atom combinations, making it very versatile. In addition, it can be synthesized at a low temperature permitting a relatively easy synthesis by a broad range of methods. The monovalent cation A (formamidinium [FA], [12] methylammonium [MA], [13] or cesium [14]) is located in the cage of BX 6 4− octahedra, where B is the metal (commonly, lead or tin) and X a halide or combination of them. The most studied hybrid-perovskite materials are MAPbI 3 and FAPbI 3. Both compounds result in a perovskite structure, despite the difference in the tolerance factor (0.95 and 1.03, respectively, and the same octahedral factor. [15,16] MAPbI 3 is intrinsically phase stable at ambient Formamidinium-based perovskite solar cells (PSCs) present the maximum theoretical efficiency of the lead perovskite family. However, formamidinium perovskite exhibits significant degradation in air. The surface chemistry of PbS has been used to improve the formamidinium black phase stability. Here, the use of PbS nanoplatelets with (100) preferential crystal orientation is reported, to potentiate the repercussion on the crystal growth of perovskite grains and to improve the stability of the material and consequently of the solar cells. As a result, a vertical growth of perovskite grains, a stable current density of 23 mA cm −2 , and a stable incident photon to current efficiency in the infrared region of the spectrum for 4 months is obtained, one of the best stability achievements for planar PSCs. Moreover, a better reproducibility than the control device, by optimizing the PbS concentration in the perovskite matrix, is achieved. These outcomes validate the synergistic use of PbS nanoplatelets to improve formamidinium long-term stability and performance reproducibility, and pave the way for using metastable perovskite active phases preserving their light harvesting capability.

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“…[ 18,19 ] However, the full elimination of MA + must be targeted for a better stabilization. [ 20–33 ] The most popular approach for MA‐free PSCs consists in replacing MA + by Cs + and/or by Rb + cations, two alkali metals. [ 20,21,31–33 ] Several authors have developed interfacial engineering for boosting the performances of the devices.…”

Section: Introductionmentioning

confidence: 99%

“…[ 20–33 ] The most popular approach for MA‐free PSCs consists in replacing MA + by Cs + and/or by Rb + cations, two alkali metals. [ 20,21,31–33 ] Several authors have developed interfacial engineering for boosting the performances of the devices. [ 22–24,33 ] However, in the absence of MA, PSCs usually show inferior PCEs due to an insufficient quality of the PVK material.…”

Section: Introductionmentioning

confidence: 99%

A Coadditive Strategy for Blocking Ionic Mobility in Methylammonium‐Free Perovskite Solar Cells and High‐Stability Achievement

2021

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Herein, the synthesis of methylammonium‐free and bromide‐free CsxFA1−xPbI3 (FA for formamidinium) perovskite (PVK) photovoltaic layers with intrinsic outstanding properties in terms of crystallinity, defect waiving/passivation, and ionic mobility blocking by using a coadditives approach is described. It consists in mixing two chloride additives in the PVK precursor solution: potassium chloride (KCl) and ammonium chloride (NH4Cl). KCl favors the lead iodide (PbI2) precursor solubilization and results in a purer PVK phase. NH4Cl allows the control of the crystallization growth speed, leading to the formation of large crystal grains and well‐crystallized layers. By the glow‐discharge optical emission spectroscopy (GD‐OES) technique, it is directly visualized that potassium incorporated in the whole film blocks the iodide mobility by defect passivation. Also, the reduction (or suppression) of iodide mobility and the reduction (or suppression) of the J–V curve hysteresis is clearly correlated. It is found that blocking the ionic mobility is insufficient to fully stabilize the halide perovskite material which also requires the crystallization monitoring carried out in parallel by the second additive. It resulted in Cs0.1FA0.9PbI3 cells with a stabilized power conversion efficiency (PCE) of 20.02% and with superior stability.

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Microscopic Degradation in Formamidinium-Cesium Lead Iodide Perovskite Solar Cells under Operational Stressors

Cited by 200 publications

References 65 publications

Multifunctional Enhancement for Highly Stable and Efficient Perovskite Solar Cells

Multifunctional Enhancement for Highly Stable and Efficient Perovskite Solar Cells

Preferred Growth Direction by PbS Nanoplatelets Preserves Perovskite Infrared Light Harvesting for Stable, Reproducible, and Efficient Solar Cells

A Coadditive Strategy for Blocking Ionic Mobility in Methylammonium‐Free Perovskite Solar Cells and High‐Stability Achievement

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