Tuning the Interfacial Dipole Moment of Spacer Cations for Charge Extraction in Efficient and Ultrastable Perovskite Solar Cells

Qiu, Yuankun; Liang, Jianghu; Zhang, Zhanfei; Deng, Zihao; Xu, Heng; He, Maosheng; Wang, Jianli; Yang, Yajuan; Kong, Lingti; Chen, Chun‐Chao

doi:10.1021/acs.jpcc.0c09606

Cited by 68 publications

(63 citation statements)

References 74 publications

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“…The D-HLH-treated device realized an ideal value ( n ) of 1.33, whereas it was 1.91 for the control. The lower value of n for the D-HLH-treated device indicates a decrease in trap-assisted recombination, consistent with the enhanced carrier lifetime observed using TRPL [ 61 , 62 ]. Consequently, all of these observations reveal that treatment with D-HLH could substantially decrease the number of trap densities and enhance the charge extraction in the MA-free Sn–Pb alloyed perovskite layer, resulting in enhanced photovoltaic performance.…”

Section: Resultssupporting

confidence: 80%

Resolving Mixed Intermediate Phases in Methylammonium-Free Sn–Pb Alloyed Perovskites for High-Performance Solar Cells

et al. 2022

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The complete elimination of methylammonium (MA) cations in Sn–Pb composites can extend their light and thermal stabilities. Unfortunately, MA-free Sn–Pb alloyed perovskite thin films suffer from wrinkled surfaces and poor crystallization, due to the coexistence of mixed intermediate phases. Here, we report an additive strategy for finely regulating the impurities in the intermediate phase of Cs0.25FA0.75Pb0.6Sn0.4I3 and, thereby, obtaining high-performance solar cells. We introduced d-homoserine lactone hydrochloride (D-HLH) to form hydrogen bonds and strong Pb–O/Sn–O bonds with perovskite precursors, thereby weakening the incomplete complexation effect between polar aprotic solvents (e.g., DMSO) and organic (FAI) or inorganic (CsI, PbI2, and SnI2) components, and balancing their nucleation processes. This treatment completely transformed mixed intermediate phases into pure preformed perovskite nuclei prior to thermal annealing. Besides, this D-HLH substantially inhibited the oxidation of Sn2+ species. This strategy generated a record efficiency of 21.61%, with a Voc of 0.88 V for an MA-free Sn–Pb device, and an efficiency of 23.82% for its tandem device. The unencapsulated devices displayed impressive thermal stability at 85 °C for 300 h and much improved continuous operation stability at MPP for 120 h.

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Section: Resultssupporting

confidence: 80%

Resolving Mixed Intermediate Phases in Methylammonium-Free Sn–Pb Alloyed Perovskites for High-Performance Solar Cells

et al. 2022

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“…As a result, device efficiency and stability are further increased. 44,45 In the present study, fluorine is used as a probe element for X-ray photoelectron spectroscopy (XPS) chemical characterization to track the 2D perovskite layer formation. A systemic study of the 2D layer formation as a function of the synthesis parameters is performed using structural, chemical, and optoelectronic characterization techniques.…”

Section: ■ Introductionmentioning

confidence: 99%

Unraveling the Formation Mechanism of the 2D/3D Perovskite Heterostructure for Perovskite Solar Cells Using Multi-Method Characterization

et al. 2022

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The formation of a two-dimensional (2D) three-dimensional (3D) perovskite heterostructure has lately proved to be a promising way to improve the interface between the perovskite and electron/hole transport layers in perovskite solar cells, which is crucial for better device efficiency and stability. Herein, a spacer cation, 4-fluorophenethylammonium iodide, in isopropyl alcohol was used to form a thin 2D perovskite layer on top of a 3D triple-cation perovskite by a spin-coating deposition process. Therefore, a significant improvement in the device open-circuit voltage is obtained, leading to an enhanced power conversion efficiency. The formation mechanism of the 2D perovskite layer was studied by analyzing the structural, chemical, and optoelectronic properties of the layer, while varying several synthesis parameters. We reveal the presence of bromide inside the 2D phase and conclude with the existence of a concomitant formation mechanism, besides the most commonly described one involving the lead iodide (PbI2) excess contained in the 3D bulk. Therefore, we demonstrate how the stoichiometry of the 2D perovskite is affected by the chemical composition of the 3D layer underneath. This work provides new insights into the synthesis mechanisms of 2D/3D perovskite heterostructures, which could help to optimize their fabrication processes and develop new efficient and functional 2D/3D structures.

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“…Very recently, the 4‐trifluoromethylphenylethylamine iodide (CF 3 PEAI, Figure ) or CF 3 PEAI‐based 2D layered perovskite was used to optimize the performance of PSCs on rigid substrate, exhibiting excellent effects on passivating defects and facilitating hole transfer. [ 22–24 ] Herein, efficient f‐PSCs were constructed via interface engineering of 2D/3D perovskite, i.e., the incorporation of a 2D perovskite (CF 3 PEA) 2 (FA) n −1 Pb n I 3 n +1 on top of the 3D perovskite FA 1− x MA x PbI 3 . The ultra‐thin 2D perovskite upshifted the energy level of 3D perovskite and decreased the energy gap between 3D perovskite and the hole transport layer (HTL) 2,2“,7,7”‐tetrakis‐( N , N ‐di(4‐methoxyphenyl‐amino)‐9,9'‐spirobi‐fluorene (Spiro‐OMeTAD), which facilitated the hole transfer due to the reduced energy barriers and charge extraction losses at the interface.…”

Section: Introductionmentioning

confidence: 99%

Creating a Dual‐Functional 2D Perovskite Layer at the Interface to Enhance the Performance of Flexible Perovskite Solar Cells

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Huang

Chang

et al. 2021

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Flexible perovskite solar cells (f‐PSCs) have been attracting tremendous attention due to their potentially commercial prospects in flexible energy system and mobile energy system. Reducing the energy barriers and charge extraction losses at the interfaces between perovskite and charge transport layers is essential to improve both efficiency and stability of f‐PSCs. Herein, 4‐trifluoromethylphenylethylamine iodide (CF3PEAI) is introduced to form a 2D perovskite at the interface between perovskite and hole transport layer (HTL). It is found that the 2D perovskite plays a dual‐functional role in aligning energy band between perovskite and HTL and passivating the traps in the 3D perovskite, thus reducing energy loss and charge carrier recombination at the interface, facilitating the hole transfer from perovskite to the Spiro‐OMeTAD. Consequently, the photovoltaic performance of f‐PSCs is significantly improved, leading to a power conversion efficiency (PCE) of 21.1% and a certified PCE of 20.5%. Furthermore, the long‐term stability of f‐PSCs is greatly improved through the protection of 2D perovskite layer to the underlying 3D perovskite. This work provides an excellent strategy to produce efficient and stable f‐PSCs, which will accelerate their potential applications.

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Tuning the Interfacial Dipole Moment of Spacer Cations for Charge Extraction in Efficient and Ultrastable Perovskite Solar Cells

Cited by 68 publications

References 74 publications

Resolving Mixed Intermediate Phases in Methylammonium-Free Sn–Pb Alloyed Perovskites for High-Performance Solar Cells

Resolving Mixed Intermediate Phases in Methylammonium-Free Sn–Pb Alloyed Perovskites for High-Performance Solar Cells

Unraveling the Formation Mechanism of the 2D/3D Perovskite Heterostructure for Perovskite Solar Cells Using Multi-Method Characterization

Creating a Dual‐Functional 2D Perovskite Layer at the Interface to Enhance the Performance of Flexible Perovskite Solar Cells

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