A Novel Dopant‐Free Triphenylamine Based Molecular “Butterfly” Hole‐Transport Material for Highly Efficient and Stable Perovskite Solar Cells

Wang, Shirong; Yi, Chenyi; Wei, Peng; Bi, Xiangdong; Luo, Jingshan; Jacopin, Gwenolé; Li, Xianggao; Xiao, Yin; Zakeeruddin, Shaik M.; Grätzel, Michaël

doi:10.1002/aenm.201600401

Cited by 164 publications

(100 citation statements)

References 38 publications

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“…[58,59,79] Due to the highly branched structures, these molecules showed insignificant aggregation or crystallization in the solid films. The differences between these molecules are the number of branched arms and their conjugation length.…”

Section: Wwwadvancedsciencenewscommentioning

confidence: 99%

Less is More: Dopant‐Free Hole Transporting Materials for High‐Efficiency Perovskite Solar Cells

Zhou

Wen

Gao

2018

Advanced Energy Materials

251

217

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years, the demands for reducing the fabrication costs and the energy payback time of photovoltaic devices led to the invention of emerging third-generation PV technologies, such as dye-sensitized solar cells (DSSCs), organic photovoltaic (OPV), quantum dots solar cells, and the latest perovskite solar cells (PSCs). Among them, PSC is the only technology that combines both merits of low processing energy cost and high power conversion efficiency (PCE), which makes it possible to replace the silicon-based PV technology.Since the first reports by Bach and Grätzel et al. about the use of 2,2′,7,7′tetrakis(N,N-di-p-methoxyphenylamine)-9,9′-spirobifluorene (spiro-OMeTAD) as the hole-transporting material (HTM) in solid-state DSSCs (ssDSSC), spiro-OMeTAD becomes the benchmark of all the new HTMs developed for ssDSSC and PSCs. Contrary to the popular myth, spiro-OMeTAD is not completely amorphous but a semi-crystalline organic p-type semiconductor with a glass transition temperature of 121 °C and a melting point of 246 °C. [1] Its chemical structure is shown in Figure 1a and Grätzel's lab first revealed the crystal structure in 2014 [2] ( Figure 1b). It has a large bandgap of 2.98 eV and yields almost colorless thin films when deposited from solution in organic solvents such as toluene or chlorobenzene. The first oxidation potential of spiro-OMeTAD is found to be approximately −5.1 eV as derived from electrochemical and photoelectron spectroscopy measurements. [3] In the case of the solid-state PSCs reported since 2012, [4,5] the PCE of lab-made devices has increased from 9.7% [6] to above 21% [7] in 2017, owing to the improvement in the perovskite composition and device engineering. However, on account of several desirable properties, (i) favorable glass transition temperature; (ii) reasonable solubility; (iii) proper ionization potential; (iii) low visible light absorption; and (iv) appropriate solid-state morphology, spiro-OMeTAD has remained as the material of choice when high PCEs are demanded. Due to the fact that spiro-OMeTAD suffers from a relatively low conductivity in its pristine form, all the eyecatching PCEs were achieved by adding additives and/or dopants-a standard technique used to tune the electrical properties of both organic and inorganic semiconductors. Typical additives including 4-tert-butylpyridine (TBP) and lithium bis(trifluoromethyl sulfonyl)imide (LiTFSI) were added to the spin-coating formulation of spiro-MeOTAD and Perovskite solar cells have delivered power conversion efficiency beyond 22% in less than seven years, implying the potential for the paradigm shift of lowcost photovoltaics with high efficiency and low embedded energy. Besides the "perovskite fever," the development of new hole transport materials (HTM), especially dopant-free HTMs, is another research hotspot. This is because the currently used HTMs, such as spiro-OMeTAD derivatives, require additional chemical doping process to ensure sufficient conductivity and proper ionic potential level for efficient hole transport and colle...

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Section: Wwwadvancedsciencenewscommentioning

confidence: 99%

Less is More: Dopant‐Free Hole Transporting Materials for High‐Efficiency Perovskite Solar Cells

Zhou

Wen

Gao

2018

Advanced Energy Materials

251

217

View full text Add to dashboard Cite

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“…However, the Achilles heel of PeSCs is their stability resisting high temperature, illumination and humidity. Through ETL or HTL property improvement [82][83][84][85][86], interfaces engineering [87][88][89] and active layer modification [90], the device stability can be improved. Utilizing 2D perovskite as the photoactive layer offers a strategy for stable solar cells with simple spin-coating process.…”

Section: Applications Of 2d Perovskite In Solar Cellsmentioning

confidence: 99%

Two-dimensional organic-inorganic hybrid perovskite: from material properties to device applications

Cai

Cheng

et al. 2018

Sci. China Mater.

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“…[18][19][20][21][22][23][24][25][26] An alternative chemical approach for designing high efficient HTMs is based on polycyclic aromatics as a central core, such as pentacene, [27] triazatruxene, [28] thiolated nanographene [29] or benzotrithiophene, [30] endowed with arylamines derivatives. These -conjugated structures show excellent holetransporting properties due to the stacking of the planar structure through intramolecular - interactions, which lead to excellent power conversion efficiencies.…”

Section: Introductionmentioning

confidence: 99%

High‐Efficiency Perovskite Solar Cells Using Molecularly Engineered, Thiophene‐Rich, Hole‐Transporting Materials: Influence of Alkyl Chain Length on Power Conversion Efficiency

Zimmermann

Urieta‐Mora

Gratia

et al. 2016

Advanced Energy Materials

135

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The synthesis and characterization of a series of novel small-molecule hole-transporting materials (HTMs) based on an anthra [1,2-b:4,3-b′:5,6-b′′:8,7-b′′′]tetrathiophene (ATT) core are reported. The new compounds follow an easy synthetic route and have no need of expensive purification steps. The novel HTMs were tested in perovskite solar cells (PSCs) and power conversion efficiencies (PCE) of up to 18.1 % under 1 sun irradiation were 2 measured. This value is comparable with the 17.8 % efficiency obtained using spiroOMeTAD as a reference compound. Similarly, a significant quenching of the Photoluminescence in the first nanosecond is observed, indicative of effective hole transfer.Additionally, the influence of introducing aliphatic alkyl chains acting as solubilizers on the device performance of the ATT molecules is investigated. Replacing the methoxy groups on the triarylamine sites by butoxy-, hexoxy-or decoxy-substituents greatly improved the solubility of the compounds without changing the energy levels, yet at the same time significantly decreasing the conductivity as well as the PCE, 17.3 % for ATT-OBu, 15.7 % for ATT-OHex and 9.7 % for ATT-ODec.

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A Novel Dopant‐Free Triphenylamine Based Molecular “Butterfly” Hole‐Transport Material for Highly Efficient and Stable Perovskite Solar Cells

Cited by 164 publications

References 38 publications

Less is More: Dopant‐Free Hole Transporting Materials for High‐Efficiency Perovskite Solar Cells

Less is More: Dopant‐Free Hole Transporting Materials for High‐Efficiency Perovskite Solar Cells

Two-dimensional organic-inorganic hybrid perovskite: from material properties to device applications

High‐Efficiency Perovskite Solar Cells Using Molecularly Engineered, Thiophene‐Rich, Hole‐Transporting Materials: Influence of Alkyl Chain Length on Power Conversion Efficiency

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