Fluorinated Low‐Dimensional Ruddlesden–Popper Perovskite Solar Cells with over 17% Power Conversion Efficiency and Improved Stability

Shi, Jishan; Gao, Yerun; Gao, Xiang; Zhang, Yun; Zhang, Junjie; Jing, Xin; Shao, M.

doi:10.1002/adma.201901673

Cited by 240 publications

(298 citation statements)

References 40 publications

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“…As shown in Figure 1b, the three cutting methods along the 〈100〉, 〈110〉, and 〈111〉 crystal directions will form three 2D perovskites with the structural formulas A′ 2 A n−1 B n X 3n+1 , A 2 A′ m B m X 3m+2 , and A′ 2 A q−1 B q X 3q+3 , respectively. Among them, the shearing method along the 〈100〉 crystal direction is the most common, and it can form three 2D perovskite phases, Ruddlesedn-Popper (R-P) [53,54] Dion-Jacobson (D-J) [55][56][57] and alternating cations in the interlayer space (ACI). [58][59][60] Their structures are illustrated in Figure 2a.…”

Section: Crystal Structurementioning

confidence: 99%

Crystallization Kinetics in 2D Perovskite Solar Cells

Wang

Lei

et al. 2020

Advanced Energy Materials

149

124

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volatile decomposition [23] or halide segregation are often observed in hybrid perovskites under various stress conditions (light, [24] thermal, [25] and electric fields [26]); 4) spontaneous phase transition easily occurs for perovskite with unstable crystal structures, particularly for inorganic perovskite. [27-29] To improve the stability of PSCs, researchers attempted numerous methods such as encapsulation, [30] additive engineering, [31] component engineering, [32] etc. [33] However, the PSCs' stability is yet to achieve a perfect solution. Recently, researchers found that the introduction of long-chain organic cations in 3D perovskite as 2D perovskite can block water and oxygen molecules, meanwhile, generate a steric effect to prevent phase transitions, and limit ion migration. [34-36] Hence, fabricating 2D [37,38] or 2D/3D [39-43] mixed perovskite as absorbing layers are effective approaches to improve the stability of PSCs. However, the PCE of 2D PSCs remain lower than that of the 3D ones, which is mainly attributed to the introduction of organic macromolecules that blocks the effective extraction and transport of carriers. [44,45] Fortunately, 2D perovskite usually has three arrangements, namely parallel, perpendicular to the glass substrate or randomly arranged. [46] Manipulating the orientation of the crystal and the phase distribution in the 2D solution-processed perovskite can improve the efficiency and reproducibility of the device. Among them, the most desired arrangement for PSCs is the one that perpendicular to the substrate. Therefore, studying the crystallization kinetics of 2D perovskite is curial to effectively control the film forming process and adjust the crystal orientation (perpendicular to the substrate), which can effectively avoid or reduce the adverse effects of the organic molecular layer and improve device efficiency. [47,48] Nevertheless, few review articles were published on this subject. In this review, we mainly focus on the key issue for controlling crystallization kinetics and summarizing the research progress of their effects on various types of 2D PSCs. We also discuss the crystal/natural quantum well (QW) structure and the original stability for 2D PSCs in detail. Finally, remaining challenges and outlooks are presented. 2. Crystal and Natural Quantum Well Structure The material structure has a substantial impact on performance. [49-51] Properties of 2D and 3D perovskites differ 2D perovskites demonstrate higher moisture stability, oxygen content, thermal stability, and a significantly lower ion migration/phase transition occurrence in comparison to 3D perovskite. These advantages imply huge potential for 2D perovskite in commercial applications in the photovoltaic field. However, the horizontal arrangement of the organic layer severely hinders the transport of carriers, and thus, the power conversion efficiency of 2D perovskite solar cells (PSCs) is significantly lower than that of 3D. Controlling the crystallization orientation to achieve rapid carrier transport can effe...

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Section: Crystal Structurementioning

confidence: 99%

Crystallization Kinetics in 2D Perovskite Solar Cells

Wang

Lei

et al. 2020

Advanced Energy Materials

149

124

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“…[ 10,11 ] In addition, through rational design of organic spacer cations with highly conductive conjugated spacers, it was found that the enhanced interplane coupling in 2D perovskites could efficiently promote charge transport. [ 12–14 ] However, RPP films with large n values exhibit more features like their 3D counterparts and a trade‐off between the PCE and stability has to be made in such case. [ 10,15 ]…”

Section: Introductionmentioning

confidence: 99%

Coordination Engineering of Single‐Crystal Precursor for Phase Control in Ruddlesden–Popper Perovskite Solar Cells

Qin

Zhong

Intemann

et al. 2020

Advanced Energy Materials

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efficiencies (PCE). [1,2] However, the intrinsic instability of 3D perovskite materials still remains unresolved. [3,4] Inert bulky organic cations can not only enhance their structural stability via strong interactions between covering organic cations and the [PbI 6 ] − units, but also block moisture from penetrating and corroding inner inorganic layers. [5,6] By incorporation of a larger cation into the 3D structure, the most common type is the (100)-oriented cutting direction, forming representative Ruddlesden-Popper perovskite (RPP) with a chemical formula (A′) 2 (A) n−1 Pb n I 3n+1 (A′ is a primary monovalent cations). [7,8] Unfortunately, the confinement effects of organic spacers also lead to a strong quantum and dielectric confinement in 2D perovskite. Moreover, the decreased conductivity of the organic layers prevents the carrier charge transport between perovskite quantum wells. [9] Thus, RPP exhibits a wider bandgap, a higher exciton binding energy (E b ), and lower charge mobility relative to the 3D perovskites, which results in poor efficiencies. Note that a weak quantum confinement would arise from an increase thickness of layers (n value), leading to a remarkable decrease in the optical bandgap, making it highly desirable to increase the number (n ≥ 4) of inorganic sheets between two adjacent organic spacers by forming quasi-2D structures. [10,11] In addition, through rational design 2D Ruddlesden-Popper perovskites (RPPs) have recently drawn significant attention because of their structural variability that can be used to tailor optoelectronic properties and improve the stability of derived photovoltaic devices. However, charge separation and transport in 2D perovskite solar cells (PSCs) suffer from quantum well barriers formed during the processing of perovskites. It is extremely difficult to manage phase distributions in 2D perovskites made from the stoichiometric mixtures of precursor solutions. Herein, a generally applicable guideline is demonstrated for precisely controlling phase purity and arrangement in RPP films. By visually presenting the critical colloidal formation of the single-crystal precursor solution, coordination engineering is conducted with a rationally selected cosolvent to tune the colloidal properties. In nonpolar cosolvent media, the derived colloidal template enables RPP crystals to preferentially grow along the vertically ordered alignment with a narrow phase variation around a target value, resulting in efficient charge transport and extraction. As a result, a recordhigh power conversion efficiency (PCE) of 14.68% is demonstrated for a (TEA) 2 (MA) 2 Pb 3 I 10 (n = 3) photovoltaic device with negligible hysteresis. Remarkably, superior stability is achieved with 93% retainment of the initial efficiency after 500 h of unencapsulated operation in ambient air conditions.

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“…[19][20][21][22] These 2D PVKs can still be solution-processed and uniquely come with the quantum well structure formed by lead halide layers separated by hydrophobic organic cation spacer layers. [19][20][21][22] These 2D PVKs can still be solution-processed and uniquely come with the quantum well structure formed by lead halide layers separated by hydrophobic organic cation spacer layers.…”

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confidence: 99%

Flexible Quasi‐2D Perovskite/IGZO Phototransistors for Ultrasensitive and Broadband Photodetection

et al. 2019

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In the past decade, high-performance, low-cost, and robust photodetectors have become one of the key components for a wide range of commercial systems, including environment and security monitoring, [1] wearable electronics, [2] free-space communications, [3] and biomedical diagnostics, [4] etc. As inspired by these applications, various emerging materials, such as quantum dots, [5] carbon nanotubes, [6] graphene, [7] and transition-metal dichalcogenides, [8] are extensively explored for the efficient photodetection. In particular, organic-inorganic hybrid perovskites (OHPs) are lately considered as the superior light-harvesting materials for photodetectors owning to their unique advantages of high optical absorption coefficient, long exciton diffusion length, and low binding energy of exciton. [9][10][11] Although these OHP materials can be easily prepared by cost-effective solution-based processes to meet the ever-increasing consumer demands for large-area and flexible optoelectronics, their photodetectors usually exhibit the relatively low responsivity because of the limited carrier mobility as well as the absence of photoconductive gain (G) mechanism that can induce multiple charge carriers by one incident photon.In order to tackle these insufficient device performances, hybrid phototransistors by simply integrating perovskites (PVKs) with different 2D materials (e.g., graphene, [12] black phosphorus, [13,14] MoS 2 , [15] and WSe 2 [16] ) have been proposed and demonstrated. By using these hybrid heterostructures, upon illumination, the photoexcited charge carriers can be spatially separated at the hetero-interface in order to prolong their carrier lifetimes, which subsequently improves the photoconductive gain of the system. However, there are still significant concerns regarding the high fabrication cost and low production yield of 2D materials for the realization of such photodetectors. At the same time, due to the low formation energy, PVK photodetectors are generally susceptible to degradation upon air and moisture exposure. In this case, tremendous efforts have then been invested to explore effective approaches to enhance the ambient-stability of these devices. [17,18] Among many latest advances, recent breakthroughs in achieving the 2D Ruddlesden-Popper phase of PVKs with the chemical formula of (RNH 3 ) 2 (A) n−1 M n X 3n+1 , where RNH 3 is a large size or long-chain organic cation, A is a regular cation, M is a divalent Organic-inorganic hybrid perovskites (PVKs) have recently emerged as attractive materials for photodetectors. However, the poor stability and low electrical conductivity still restrict their practical utilization. Owing to the quantum-well feature of two-dimensional (2D) Ruddlesden-Popper PVKs (2D PVKs), a promising quasi-2D PVK/indium gallium zinc oxide (IGZO) heterostructure phototransistor can be designed. By using a simple ligand-exchange spin-coating method, quasi-2D PVK fabricated on flexible substrates exhibits a desirable type-II energy band alignment, which facilitates effect...

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Fluorinated Low‐Dimensional Ruddlesden–Popper Perovskite Solar Cells with over 17% Power Conversion Efficiency and Improved Stability

Cited by 240 publications

References 40 publications

Crystallization Kinetics in 2D Perovskite Solar Cells

Crystallization Kinetics in 2D Perovskite Solar Cells

Coordination Engineering of Single‐Crystal Precursor for Phase Control in Ruddlesden–Popper Perovskite Solar Cells

Flexible Quasi‐2D Perovskite/IGZO Phototransistors for Ultrasensitive and Broadband Photodetection

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