Effects of heteroatom substitution in spiro-bifluorene hole transport materials

Zhao, Haiyan; Fu, Weifei; Yan, Lijia; Miao, Jingsheng; Yu, Hongtao; He, Yaowu; Goto, Osamu; Meng, Hong; Chen, Hongzheng; Huang, Wei

doi:10.1039/c6sc00973e

Cited by 96 publications

(73 citation statements)

References 39 publications

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“…The better stability could be due to reduced symmetry of the spiro‐MeOTAD and therefore the HTM is less prone to crystallization . Similarly, Hu et al substituted the methoxy groups of the spiro‐MeOTAD by methylsulfanyl, N,N ‐dimethylamino and ethyl groups, making three new HTMs, namely, spiro‐S, spiro‐N, spiro‐E, respectively. Inverted PSCs were fabricated with these new HTMs.…”

Section: Alternative Htms Based On Spiro‐meotad Structurementioning

confidence: 99%

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Recent Advances in Spiro‐MeOTAD Hole Transport Material and Its Applications in Organic–Inorganic Halide Perovskite Solar Cells

Hawash

Ono

2017

Adv Materials Inter

357

336

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2,2′,7,7′‐tetrakis‐(N,N‐di‐4‐methoxyphenylamino)‐9,9′‐spirobifluorene (spiro‐MeOTAD) hole transport material (HTM) is a milestone in the history of perovskite solar cells (PSCs). Proper choice of HTMs is key factor for efficient charge extraction and stability in solar cells. Spiro‐MeOTAD is proven to be the most suitable HTM for testing PSCs due to its facile implementation and high performance. Similarly, spiro‐MeOTAD is receiving attention in other applications other than in solar cells due to its desirable properties. However, spiro‐MeOTAD is under debate regarding the topics of cost‐performance, long‐term stability, degradation issues (induced by temperature, additives, film quality, and environmental conditions), coating technologies compatibility, reliance on additives, and hysteresis. In this review, the advent of spiro‐MeOTAD, and related aforementioned issues about spiro‐MeOTAD are discussed. In addition, spiro‐MeOTAD properties, alternative and new additives, other applications, and new HTMs that is comparable or outperforms spiro‐MeOTAD in PSCs are summarized. In the outlook, the future research directions based on reported results that warrant further investigations are outlined.

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Section: Alternative Htms Based On Spiro‐meotad Structurementioning

confidence: 99%

“…Spiro‐S substantially outperformed spiro‐MeOTAD under the same fabrication conditions with an average PCE of 15.1% compared to 10.4%. Also, Spiro‐E and Spiro‐S exhibited greater hydrophobicity with slightly deeper HOMO energy levels …”

Section: Alternative Htms Based On Spiro‐meotad Structurementioning

confidence: 99%

Recent Advances in Spiro‐MeOTAD Hole Transport Material and Its Applications in Organic–Inorganic Halide Perovskite Solar Cells

Hawash

Ono

2017

Adv Materials Inter

357

336

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“…The advantage of these two materials (denoted as DFS and FS) over those previously reported [22] is that the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energies of these two materials resemble those of Spiro-OMeTAD. The advantage of these two materials (denoted as DFS and FS) over those previously reported [22] is that the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energies of these two materials resemble those of Spiro-OMeTAD.…”

Section: Introductionmentioning

confidence: 99%

“…[18] Later, Saliba et al [19] reported the synthesis of (2′7′-bis(bis(4-methoxyphenyl)amino)spiro[cyclopenta[2,1-b:3,4-b′]dithiophene-4,9′-fluorene] (commonly known as FDT) that contains two thiophene groups as the π-linker one of the Spiro-OMeTAD fluorenes. In another work, Hu et al [22] introduced three new spirofluorene-based HSMs by replacing the paramethoxy substituent in Spiro-OMeTAD with methylsulfanyl, N,N-dimethylamino, and ethyl groups. Other studies suggested that the presence of thiophene [20] or phenothiazine [21] is beneficial for charge extraction due to the potential trap passivation via Pb-S interactions.…”

Section: Introductionmentioning

confidence: 99%

Rationalizing the Molecular Design of Hole‐Selective Contacts to Improve Charge Extraction in Perovskite Solar Cells

Wang

Mosconi

Wolff

et al. 2019

Advanced Energy Materials

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Two new hole selective materials (HSMs) based on dangling methylsulfanyl groups connected to the C‐9 position of the fluorene core are synthesized and applied in perovskite solar cells. Being structurally similar to a half of Spiro‐OMeTAD molecule, these HSMs (referred as FS and DFS) share similar redox potentials but are endowed with slightly higher hole mobility, due to the planarity and large extension of their structure. Competitive power conversion efficiency (up to 18.6%) is achieved by using the new HSMs in suitable perovskite solar cells. Time‐resolved photoluminescence decay measurements and electrochemical impedance spectroscopy show more efficient charge extraction at the HSM/perovskite interface with respect to Spiro‐OMeTAD, which is reflected in higher photocurrents exhibited by DFS/FS‐integrated perovskite solar cells. Density functional theory simulations reveal that the interactions of methylammonium with methylsulfanyl groups in DFS/FS strengthen their electrostatic attraction with the perovskite surface, providing an additional path for hole extraction compared to the sole presence of methoxy groups in Spiro‐OMeTAD. Importantly, the low‐cost synthesis of FS makes it significantly attractive for the future commercialization of perovskite solar cells.

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“…[25] To date, al ot of small molecules, such as carbazole-based derivatives, 3,4-ethylenedioxythiophene, benzotrithiophene derivatives, phenoxazine-cored structure, spiro[fluorine-9,9'-xanthene],a nd spiro-OMeTAD derivatives, have been appliedi nP SCs and considerable efficiency has been accomplished. [31][32][33][34][35][36][37] Of the various HTMs,t he tetraphenylethylene-baseds mallm olecules have provedt heir potentialr ecently,a nd three independent groups, includingo urs, have confirmed aP CE of approximately 13 % with the use of N,N-di(4-methoxyphenyl)aminophenyl-substituted tetraphenylethylene (TPE-4DPA, Scheme1). [39,40] Furthermore,t he TPE derivativehas been provedtobeable to replace PEDOT(poly(3,4-ethylenedioxythiophene)):PSS(polystyrene sulfonate) in invertedP SCs.…”

Section: Introductionmentioning

confidence: 99%

m‐Methoxy Substituents in a Tetraphenylethylene‐Based Hole‐Transport Material for Efficient Perovskite Solar Cells

Liu

Wang

et al. 2016

Chemistry A European J

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Three tetrapheynlethylene derivatives (N,N-di(4-methoxyphenyl)aminophenyl-substituted tetraphenylethylene; TPE-4DPA) with different methoxy positions (pp-, pm-, and po-) have been synthesized and characterized. The methoxy groups can control the oxidation potential of the materials, and the electronic properties of the derivatives were affected by the position of the methoxy substituents. These compounds were synthesized in a facile and cost-effective way, and were applied as hole-transport materials in perovskite solar cells. The corresponding cell performances were compared with respect to their structure modifications, and it was found that the derivative with m-OMe substituents showed the highest power conversion efficiency (PCE) of 15.4 %, with a J value of 20.04 mA cm , a V value of 1.07 V, and a fill factor (FF) value of 0.72, which is higher than the p-OMe and o-OMe substituents. Moreover, the PCE of pm-TPE-4DPA is comparable with that of the state-of-the-art 2,2',7,7'-tetrakis(N,N'-di-p-methoxyphenylamine)-9,9'-spirobifluorene under identical conditions.

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Effects of heteroatom substitution in spiro-bifluorene hole transport materials

Abstract: By introducing the heteroatom into the benchmark hole transport material Spiro-MeOTAD, the energy level of hole transport materials can be tuned.

Cited by 96 publications

References 39 publications

Recent Advances in Spiro‐MeOTAD Hole Transport Material and Its Applications in Organic–Inorganic Halide Perovskite Solar Cells

Recent Advances in Spiro‐MeOTAD Hole Transport Material and Its Applications in Organic–Inorganic Halide Perovskite Solar Cells

Rationalizing the Molecular Design of Hole‐Selective Contacts to Improve Charge Extraction in Perovskite Solar Cells

m‐Methoxy Substituents in a Tetraphenylethylene‐Based Hole‐Transport Material for Efficient Perovskite Solar Cells

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