Efficient, stable solar cells by using inherent bandgap of α-phase formamidinium lead iodide

Min, Hanul; Kim, Maengsuk; Lee, Seungun; Kim, Hyeonwoo; Kim, Gwisu; Choi, Keunsu; Lee, Jun Hee; Seok, Sang Il

doi:10.1126/science.aay7044

Cited by 1,031 publications

(892 citation statements)

References 51 publications

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“…The reduced pseudo‐ total trap density can be further evaluated through SCLC model on hole‐only device of ITO/PEDOT:PSS/perovskite/spiro‐OMeTAD/Au. [ 61–63 ] The average trap densities determined from the dark current–voltage characteristics (hole‐only, Figure S18b, Supporting Information) based on Equation S2, Supporting Information, are 3.63 × 10 15 cm −3 and 2.56 × 10 15 cm –3 for the control and NMAI‐treated samples, respectively. The estimated results show that the surface trap density is reduced after NMAI treatment, which is well in line with the PL and TRPL measurements.…”

Section: Resultsmentioning

confidence: 99%

Efficient Perovskite Solar Cells by Reducing Interface‐Mediated Recombination: a Bulky Amine Approach

Liang

Luo

et al. 2020

Advanced Energy Materials

221

199

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meantime, the ease of the solution process at low temperature renders this technology up-and-coming for large-scale low-cost manufacture. However, these solution-processed perovskite films are usually polycrystalline, which readily form defects at the grain boundaries and on the surface of the films. [1][2][3][4][5][6] Such defects are the center of non-radiative recombination of photo-generated electrons and holes, which causes shorter carrier lifetime and lower open-circuit voltage (V OC ). Hence, in real devices, higher recombination rate occurs close to the interface of the sequentially deposited layers. For typical n-i-p perovskite solar cells (PSCs), the perovskite/hole transport layer (HTL) interface holds the high defect density, such as cation/anion vacancy and dangling bonds, etc., [7,8] resulting in defect-assisted recombination. Additionally, the energy level mis-alignment near the interface due to quasi-fermi level pinning will increase recombination velocity [9] and the recombination loss occurs inevitably across interfaces between holes in HTL and minority carriers (electron) in the perovskite, or HTL themselves. [10,11] These existing recombination loss channels at the surface/ interface of the perovskite will severely limit the V OC and overall efficiency of PSCs.Many studies have demonstrated that passivation is an efficient method to lessen the non-radiative recombination loss at the surface/interface of the perovskite in n-i-p PSCs. For example, excess PbI 2 [4,[12][13][14] was believed to passivate the grain boundaries and interface of electron transport layer with perovskite; conjugated polymers [15] and insulating poly(methyl methacrylate) [16,17] were also used to passivate the interface of perovskite/HTL. Recently, various ammonium halide compounds, [8,18,19] especially bulky organic ammonium halide salts were adopted to passivate the surface of perovskite, such as 1,8-octanediammonium iodide, [3] adamantylammonium hydroiodide, [7] (fluorine-)phenylethylammonium iodide (F-)PEAI, [20][21][22][23] n-hexyl trimethyl ammonium bromide, [24] etc. They could interact with the undercoordinated ions or form low-dimensional perovskite phases to passivate the surface/ interface of bulk perovskite. The stability of devices was also usually improved due to the suppression of ionic migration by the packed organic moiety or the formation of hydrophobic low-dimensional perovskites. [7,23,25] A very recent work by Jiang et al. found exceptionally that the insulating PEAI salt, rather than the 2D layered PEA 2 PbI 4 perovskite, served as a moreThe presence of non-radiative recombination at the perovskite surface/ interface limits the overall efficiency of perovskite solar cells (PSCs). Surface passivation has been demonstrated as an efficient strategy to suppress such recombination in Si cells. Here, 1-naphthylmethylamine iodide (NMAI) is judiciously selected to passivate the surface of the perovskite film. In contrast to the popular phenylethylammonium iodide, NMAI post-treatment primarily leaves NMAI sal...

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Section: Resultsmentioning

confidence: 99%

Efficient Perovskite Solar Cells by Reducing Interface‐Mediated Recombination: a Bulky Amine Approach

Liang

Luo

et al. 2020

Advanced Energy Materials

221

199

View full text Add to dashboard Cite

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“…Perovskite solar cells (PSCs) based on organic–inorganic perovskites with 3D crystal structures have seen rapid progress in recent years, as demonstrated by the high power conversion 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.…”

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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“…By using CuPC as hole transport layer (HTL), the MDACl 2 doped FAPbI 3 device exhibited higher humidity stability, retaining >90% of the initial PCE after 70 h under high humidity (85% RH, 25 °C), while the PCE of pure FAPbI 3 device reduced to 40% of the initial value (Figure 12f). [ 40 ] Besides the Cl based additive, Yu et al demonstrated an effective way to fabricate high‐quality FA based film by adding a small amount of lead thiocyanate [Pb(SCN) 2 ] to the precursor. The addition of Pb(SCN) 2 could effectively enlarge the grain size of FA 1− x Cs x PbI 3 perovskite film and significantly increased the carrier lifetime.…”

Section: Phase Stability Of Fapbi3‐based Solar Cellsmentioning

confidence: 99%

“…Reproduced with permission. [ 40 ] Copyright 2019, AAAS. g) PCE versus storage time of FAPbI 3 and FA 0.8 Cs 0.2 PbI 3 perovskite solar cells with and without 0.5 % Pb(SCN) 2 as additive, respectively.…”

Section: Phase Stability Of Fapbi3‐based Solar Cellsmentioning

confidence: 99%

Recent Advances in Improving Phase Stability of Perovskite Solar Cells

Qiu

Huang

et al. 2020

Small Methods

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Organic–inorganic hybrid perovskite solar cells (PSCs) have demonstrated high efficiency and improved stability, which shows promising potential for commercialization. However, among all challenges, the material and device instability of the methylammonium lead iodide (MAPbI3) absorber are regarded as serious obstacles to the future development of devices for long‐term operation. Compared with conventional MAPbI3, formamidinium lead iodide (FAPbI3) and cesium lead iodide (CsPbI3) have attracted more attention due to their superior thermal stability. Due to their undesirable tolerant factor, however, these materials suffer from poor phase stability, which is worthy of careful investigation. This perspective highlights the recent progress on the phase stabilization of FAPbI3 and inorganic CsPbI3 materials with emphasis on the fundamental understanding of the origin of phase instability. In addition, strategies to fabricate corresponding devices toward high‐efficiency and long‐lifetime are discussed. This review sheds light onto the design and synthesis of FAPbI3 and inorganic CsPbI3 perovskite materials. In the end, the potential of FAPbI3 and inorganic CsPbI3 perovskite materials as stable absorbers is discussed, which promotes the development of corresponding solar cells and other optoelectronic devices for practical applications.

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Efficient, stable solar cells by using inherent bandgap of α-phase formamidinium lead iodide

Cited by 1,031 publications

References 51 publications

Efficient Perovskite Solar Cells by Reducing Interface‐Mediated Recombination: a Bulky Amine Approach

Efficient Perovskite Solar Cells by Reducing Interface‐Mediated Recombination: a Bulky Amine Approach

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

Recent Advances in Improving Phase Stability of Perovskite Solar Cells

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