Planar perovskite solar cells with long-term stability using ionic liquid additives

Bai, Sai; Da, Peimei; Li, Cheng; Wang, Zhiping; Yuan, Zhongcheng; Fu, Fan; Kawecki, Maciej; Liu, Xianjie; Sakai, Nobuya; Wang, Jacob Tse-Wei; Huettner, Sven; Buecheler, Stephan; Fahlman, Mats; Gao, Feng; Snaith, Henry J.

doi:10.1038/s41586-019-1357-2

Cited by 1,206 publications

(1,023 citation statements)

References 37 publications

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“…It can be seen that the J sc , and V oc of the device increased significantly after adding oxo-G/DA. [8,36,37] The incident photon-to-current efficiency (IPCE) spectra for the control and the perovskite:oxo-G/DA devices are displayed in Figure 4b. [30] The improvement in V oc and FF is attributed to the improved grain size and decreased pinholes.…”

Section: Characterization Of Perovskite:oxo-g/da Filmsmentioning

confidence: 99%

Ultrathin Nanosheets of Oxo‐functionalized Graphene Inhibit the Ion Migration in Perovskite Solar Cells

Zuo

Qiong

et al. 2019

Advanced Energy Materials

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Recent progress of PSCs in efficiency and stability enhancement is addressed to the change of perovskite composition and crystal optimization. By introducing mixed cations and halide to adjust the composition of the organicinorganic hybrid perovskite, the crystal structure of the perovskite can be effectively improved, which ultimately led to the increased stability and efficiency of the PSCs. Compared with the single cation/ halide perovskite (methylammonium halide, formamidinium lead halide, and cesium lead halide), the mixed perovskite not only has higher PCE but also has better heat and humid air stability. [9][10][11][12] For mixed cation/halide perovskites, despite good optoelectronic properties, the mixing of multiple cations and halogens is prone to localized ionic enrichment during preparation, annealing, and operation. At the same time, as the cation and halide ions move in the builtin electric field of the device, local positive and negative ion vacancies are formed. These defects will cause significant hysteresis in the device and ultimately affect the performance of the device. [13][14][15][16][17] A series of studies on both experimental and theoretical methods [13,18,19] have been reported. Constraining Mixed cation/halide perovskites have led to a significant increase in the efficiency and stability of perovskite solar cells. However, mobile ionic defects inevitably exacerbate the photoinduced phase segregation and selfdecomposition of the crystal structure. Herein, ultrathin 2D nanosheets of oxo-functionalized graphene/dodecylamine (oxo-G/DA) are used to solve ion migration in cesium (Cs)-formamidinium (FA)-methylammonium (MA) triple-cation-based perovskites. Based on the superconducting carbon skeleton and functional groups that provide lone pairs of electrons on it, the ultrathin 2D network structure can fit tightly on the crystals and wrap them, isolating them, and thus reducing the migration of ions within the built-in electric field of the perovskite film. As evidence of the formation of sharp crystals with different orientation within the perovskite film, moiré fringes are observed in transmission electron microscopy. Thus, a champion device with a power conversion efficiency (PCE) of 21.1% (the efficiency distribution is 18.8 ± 1.7%) and a remarkable fill factor of 81%, with reduced hysteresis and improved long-term stability, is reported. This work provides a simple method for the improvement of the structural stability of perovskite in solar cells.

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Section: Characterization Of Perovskite:oxo-g/da Filmsmentioning

confidence: 99%

Ultrathin Nanosheets of Oxo‐functionalized Graphene Inhibit the Ion Migration in Perovskite Solar Cells

Zuo

Qiong

et al. 2019

Advanced Energy Materials

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“…Ion migration also exists in perovskite photovoltaics (PVs). However, due to the low field present during operation, ion migration does not appear to be a severe problem affecting the operational lifetime of perovskite PVs [27]. On the contrary, it is not uncommon to see a perovskite LED degrades to half of their initial efficiency within hours [16,18,28,29] or even minutes [17,[30][31][32][33][34] due to ion migration under an applied electric field.…”

Section: Introductionmentioning

confidence: 99%

Operational stability of perovskite light emitting diodes

et al. 2020

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Organometal halide perovskite light emitting diodes (LEDs) have attracted a lot of attention in recent years, owing to the rapid progress in device efficiency. However, their short operational lifetime severely impedes the practical uses of these devices. The operating stability of perovskite LEDs are due to degradation due to ambient environment and degradation during operation. The former can be suppressed by encapsulation while the latter one is the intrinsic degradation due to the electrochemical stability of the perovskite materials. In addition, perovskites also suffer from ion migration which is a major degradation mechanism in perovskite LEDs. In this review, we specifically focus on the operational stability of perovskite LEDs. The review is divided into two parts: the first part contains a summary of various degradation mechanisms and some insight on the degradation behavior and the second part is the strategies how to improve the operational stability, especially the strategies to suppress ion migration. Based on the current advances in the literature, we finally present our perspectives to improve the device stability.

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“…[40] In that work, it was shown that treating the TiO 2 surface with BMIMBF 4 results in more efficient electron extraction, which is attributed to a decrease in the work function of the TiO 2 which improves its energy level alignment with the perovskite as well as an increase in electron mobility of the titania due to the pas sivation of trap states on the TiO 2 surface. [43] Additionally, recent work using ILs in perovskite solar cells has yielded considerable improvements to the long term stability of these devices through the incorporation of BMIMBF 4 into the perovskite precursor solution in one case [44] and 4imidazoleacetic acid hydrochloride as an interface modi fier in the other. Similar work had also previously been carried out by Wu et al using another fluorinated IL, 1ethyl3methylimida zolium hexafluorophosphate (EMIMPF 6 ).…”

Section: Introductionmentioning

confidence: 99%

Elucidating the Role of a Tetrafluoroborate‐Based Ionic Liquid at the n‐Type Oxide/Perovskite Interface

Noel

Habisreutinger

Wenger

et al. 2019

Advanced Energy Materials

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Halide perovskites are currently one of the most heavily researched emerging photovoltaic materials. Despite achieving remarkable power conversion efficiencies, perovskite solar cells have not yet achieved their full potential, with the interfaces between the perovskite and the charge‐selective layers being where most recombination losses occur. In this study, a fluorinated ionic liquid (IL) is employed to modify the perovskite/SnO2 interface. Using Kelvin probe and photoelectron spectroscopy measurements, it is shown that depositing the perovskite onto an IL‐treated substrate results in the crystallization of a perovskite film which has a more n‐type character, evidenced by a decrease of the work function and a shift of the Fermi level toward the conduction band. Photoluminescence spectroscopy and time‐resolved microwave conductivity are used to investigate the optoelectronic properties of the perovskite grown on neat and IL‐modified surfaces and it is found that the modified substrate yields a perovskite film which exhibits an order of magnitude lower trap density than the control. When incorporated into solar cells, this interface modification results in a reduction in the current–voltage hysteresis and an improvement in device performance, with the best performing devices achieving steady‐state PCEs exceeding 20%.

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Planar perovskite solar cells with long-term stability using ionic liquid additives

Cited by 1,206 publications

References 37 publications

Ultrathin Nanosheets of Oxo‐functionalized Graphene Inhibit the Ion Migration in Perovskite Solar Cells

Ultrathin Nanosheets of Oxo‐functionalized Graphene Inhibit the Ion Migration in Perovskite Solar Cells

Operational stability of perovskite light emitting diodes

Elucidating the Role of a Tetrafluoroborate‐Based Ionic Liquid at the n‐Type Oxide/Perovskite Interface

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