Defect passivation using ultrathin PTAA layers for efficient and stable perovskite solar cells with a high fill factor and eliminated hysteresis

Wang, Ming; Wang, Huaxin; Li, Wei; Hu, Xiaofei; Sun, Kuan; Zang, Zhigang

doi:10.1039/c9ta08314f

Cited by 276 publications

(147 citation statements)

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“…It can be found that all the diffraction patterns with similar crystallographic orientation for the perovskite films and these diffraction peaks belong to the typical FA 0.2 MA 0.8 P bI 3−x Cl x phase. [60] Figure 3a shows the main diffraction peak intensity is increased after MI modification compared to that of the reference one, indicating perovskite crystallization is improved by the MI modified layer. Increased perovskite crystal quality means higher absorption which has been shown by the absorption spectra as shown in Figure 2b.…”

Section: Resultsmentioning

confidence: 96%

Small Molecule Modulator at the Interface for Efficient Perovskite Solar Cells with High Short‐Circuit Current Density and Hysteresis Free

Wang

et al. 2020

Adv Elect Materials

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received much attention recently due to its excellent photoelectric properties, such as strong light-absorbing coefficient, long carrier lifetime, adjustable bandgap and simple fabrication process. [3-9] In the past few years, the power conversion efficiency (PCE) of perovskite solar cells (PSCs) has been promoted from 3.8% to 25.2% by the substantial effort, such as the additive engineering, interface engineering, and film morphology engineering. [10-14] However, the mesoporous PSCs require high sintering temperature, increasing energy consumption and device cost, which are incompatible with commercial and flexible applications. [15-17] Hence numerous efforts are conducted to fabricate the planar PSCs with well-established low-temperature and simple fabrication process. [18-20] Unfortunately, researches have shown that perovskite films in the planer PSCs prepared by one-step anti-solvent deposition have many interface defects, [21-24] which accelerate the degradation of PSCs under humidity, oxygen, thermal condition and illumination fields. [25-28] Thus, interface modification is extensively used to improve the photovoltaic performance of the PSCs. [29-33] In planar PSCs, the electron transfer layer (ETL) and hole transport layer (HTL) have crucial influences on the crystallization process of perovskite films. Meanwhile, the interfacial contacts between the ETL (or HTL) and the perovskite films affect the photogenerated carriers dynamic and thus change the overall device efficiency, stability and hysteresis. [34-38] It is well known that the enlarged grains of perovskite films and decreased interface defects boost the performance of PSCs. Accordingly, the interface modification at perovskite/HTL and perovskite/ETL interfaces have been investigated and optimized. For instance, several effective electronic transport materials (i.e., TiO 2 , ZnO, SnO 2) have been modified by inserting a passivation layer to aggrandize grain size, reduce interface recombination and increase interface carrier transmission in normal planar PSCs. [39-43] For the inverted PSCs, several organic and inorganic materials formed on HTL by interface modification for improving PCE, such as polymers poly (4-vinyl pyridine) (PVP), poly (N-90-heptadecanyl-2,7-carbazolealt-5,5-(40,70-di-2-thienyl-20,10,30-benzothiadiazole))PCDTBT), Interface engineering is widely applied in the one-step antisolvent deposition for elevating efficiency of the perovskite solar cells (PSCs). Herein, an alcohol-soluble small molecule, namely 2-mercaptoimidazole (MI), is inserted between the hole transport layer and perovskite layer to form a cross-linking bridge, which is built through: i) Coulomb interaction between the negatively charged MI and positively charged poly (3,4-ethylene dioxythiophene); ii) electrostatic interaction between imidazolium cation and iodide anion in perovskite. The cross-linking bridge can accelerate the hole transmission and inhibit interfacial recombination. Hence, by the optimum design of MI concentration, hysteresis-free devices with a hi...

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Section: Resultsmentioning

confidence: 96%

Small Molecule Modulator at the Interface for Efficient Perovskite Solar Cells with High Short‐Circuit Current Density and Hysteresis Free

Wang

et al. 2020

Adv Elect Materials

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“…Therefore, the corresponding energy level schematic of the p‐i‐n planar PSCs is shown in Figure 1h. [ 29,31 ] The well‐matched energy level between HTL and perovskite layer will reduce the carrier recombination at the interface and simultaneously suppress the energy loss of hole transport, [ 47,48 ] contributing to higher V OC and outstanding PSCs performance. [ 34,49 ]…”

Section: Resultsmentioning

confidence: 99%

Sodium Benzenesulfonate Modified Poly (3,4‐Ethylenedioxythiophene):Polystyrene Sulfonate with Improved Wettability and Work Function for Efficient and Stable Perovskite Solar Cells

Wang

et al. 2020

Solar RRL

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The increasing interest in high-performance and economical photovoltaic materials has heightened the emergency to develop the organic-inorganic hybrid halide perovskite solar cells (PSCs). Since the debut of PSCs proposed by Miyasaka et al. in 2009, the PSCs community has achieved great success such as the rocketing power conversion efficiency (PCE) from the initial 3.8% to the latest 25.5% in 2020 in single-junction architectures, and to 29.1% in silicon-based tandem cells. [1-5] This eye-catching breakthrough is contributed by the numerous merits of perovskite material such as long carrier-diffusion length, proper bandgap (1.5-1.6 eV), and facile solution processing. [6-10] In general, the PSCs are classified by architecture into normal (n-i-p) and inverted (p-in) structures, where the perovskite layer is sandwiched between the electron transport layer (ETL) and hole transport layer (HTL). [11,12] For the normal-structured PSCs, metal oxides such as SnO 2 and TiO 2 are commonly used as the bottom ETL, whereas the organic materials such as Spiro-OMeTAD are used as HTL. [13,14] The PSCs feature high efficiency up to 24.82% by introducing fluorinated isomeric analogs in Spiro-OMeTAD. [15] However, the normal-structured PSCs with high PCE are usually based on mesoscopic n-type TiO 2 or insulating Al 2 O 3 to accelerate electron mobility, while the high sintering temperature (>450 C) limits the application in low-cost flexible devices. [16,17] Meanwhile, the upper HTL used organic materials is extremely costly and unstable in air. In contrast, the bottom HTL of inverted (p-in) PSCs is low-temperature processable (<100 C) and cheaper. Therefore, the inverted planar PSCs have a wider application prospect on account of lowtemperature preparation, excellent reproducibility, and negligible hysteresis. [18,19] In addition, the efficiency of the small-area inverted planar PSCs has reached a certified value of 22.3%. [20] Also the record efficiency of over 18% for a mini-module has been achieved in an aperture area of 19.276 cm 2. [21] These results indicate that the inverted structure may be more suitable for manufacturing large-area cells with long-term stability and outstanding efficiency, which means inverted planar PSCs have a better prospect in commercialization. The most common structure of the inverted PSCs is indium tin oxide (ITO)/Poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS)/perovskite/PCBM/metal electrode. [22,23] PEDOT:PSS is the most extensively used hole transfer material in inverted PSCs due to its optical transparency, high thermal stability, and good mechanical flexibility.

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“…Organic-inorganic halide perovskite solar cells (PSCs) have attracted a great amount of scientific interest during the last few years as evidenced by their rapid improvement from 3.8% [1] Large effort has been directed toward higher-performance materials for use in this inverted structure: for instance, it has been demonstrated that replacing the acidic and hygroscopic PEDOT:PSS with NiO x , [22] PTAA, [23] poly-TPD [24] and several self-assembling monolayers (SAMs) [25] can deliver solar cells superior in both performance and stability. However, while PCBM-based PSCs tend to exhibit hysteresis-free behavior, the difference between the Fermi level of PCBM and the work function of the Ag electrode leads to the formation of a Schottky barrier at the interface.…”

Section: Introductionmentioning

confidence: 99%

A Multilayered Electron Extracting System for Efficient Perovskite Solar Cells

Seitkhan

Neophytou

Hallani

et al. 2020

Adv Funct Materials

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Power conversion efficiencies of perovskite solar cells (PSCs) have rapidly increased from 3.8% to a certified 25.2% within only a decade. Eliminating possible recombination losses at the interfaces is essential to further improve both efficiency and stability of this class of emerging photovoltaic technology. Herein, a simple approach for improving the electron extraction of the PC 60 BM electron transport layer (ETL) is presented by sequentially depositing Al:ZnO (AZO) and triphenyl-phosphine oxide (TPPO) on top of it, in a p-in device configuration. The efficiency of the resulting CH 3 NH 3 PbI 3-based solar cell is shown to improve from 14.6%, measured for the control PC 60 BM-only cell, to 17.9% for double-ETL (PC 60 BM/AZO) and 19.2% for triple-ETL (PC 60 BM/AZO/ TPPO)-based devices, respectively. Optimized triple-ETL-based cells exhibit high fill factor of 82%. The combination of electrical and quantum mechanical calculations shows that efficiency improvement is attributed to reduced trapassisted recombination at the interface and better energy level alignment due to chemical interactions between PC 60 BM, AZO, and TPPO. Moreover, it is shown that the use of multilayer ETL results in better device stability (T 80 ≈ 800 h) under constant illumination. This work opens new possibilities for inexpensive highly efficient and stable multilayered contacts for PSCs by combining organic small molecules and metal oxides.

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Defect passivation using ultrathin PTAA layers for efficient and stable perovskite solar cells with a high fill factor and eliminated hysteresis

Abstract: Ultra-thin PTAA layers contribute to interface defect passivation and interface recombination reduction to improve the efficiency of perovskite solar cells.

Cited by 276 publications

References 45 publications

Small Molecule Modulator at the Interface for Efficient Perovskite Solar Cells with High Short‐Circuit Current Density and Hysteresis Free

Small Molecule Modulator at the Interface for Efficient Perovskite Solar Cells with High Short‐Circuit Current Density and Hysteresis Free

Sodium Benzenesulfonate Modified Poly (3,4‐Ethylenedioxythiophene):Polystyrene Sulfonate with Improved Wettability and Work Function for Efficient and Stable Perovskite Solar Cells

A Multilayered Electron Extracting System for Efficient Perovskite Solar Cells

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