Molecular “Flower” as the High-Mobility Hole-Transport Material for Perovskite Solar Cells

Kou, Chun; Feng, Shiyu; Li, Hongshi; Li, Wenhua; Li, Dongmei; Meng, Qingbo; Bo, Zhishan

doi:10.1021/acsami.7b13380

Cited by 34 publications

(28 citation statements)

References 31 publications

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“…[8,9] These materials should also have high temporal stability under elevated temperatures and humidity. [10][11][12] Organic HTMs are amenable to low-temperature solution processing while also being capable of mediating high power conversion efficiencies (PCEs). [13,14] Spiro-OMeTAD [15] ( Figure 1) is aw idely used organic HTM and is capable of reaching PCEs greater than 20 %w hen integrated in PSCs.…”

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confidence: 99%

Precise Control of Thermal and Redox Properties of Organic Hole‐Transport Materials

et al. 2018

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We report design principles of the thermal and redox properties of synthetically accessible spiro-based hole transport materials (HTMs) and show the relevance of these findings to high-performance perovskite solar cells (PSCs). The chemical modification of an asymmetric spiro[fluorene-9,9'-xanthene] core is amenable to selective placement of redox active triphenylamine (TPA) units.W etherefore leveraged computational techniques to investigate five HTMs bearing TPAgroups judiciously positioned about this asymmetric spiro core.Itwas determined that TPAg roups positioned about the conjugated fluorene moiety increase the free energy change for holeextraction from the perovskite layer,w hile TPAs about the xanthene unit govern the T g values.T he synergistic effects of these characteristics resulted in an HTM characterized by both al ow reduction potential ( % 0.7 Vv s. NHE) and ah igh T g value (> 125 8 8C) to yield adevice power conversion efficiency (PCE) of 20.8 %inaP SC.

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confidence: 99%

Precise Control of Thermal and Redox Properties of Organic Hole‐Transport Materials

et al. 2018

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“…NDI cores possess relatively high symmetry (i.e., various mirror planes and rotational symmetry axis). Such high molecular symmetry is also observed in other electron‐transporting cores such as diketopyrrolopyrrole (DPP), cyanoethylene, and N‐heterocycle derivatives, and hole transporting cores such as arylamine derivatives . Introducing symmetry‐breaking groups onto N ‐substituted positions of NDI cores can increase solubility by loosening the packing of NDI‐based molecules in the solid state.…”

Section: Resultsmentioning

confidence: 96%

“…Such high molecular symmetry is also observed in other electron-transporting cores such as diketopyrrolopyrrole (DPP), cyanoethylene,a nd N-heterocycle derivatives, [41,42] and hole transporting cores such as arylamine derivatives. [22][23][24] Introducing symmetry-breaking groupso nto N-substituted positions of NDI cores can increases olubility by loosening the packing of NDI-based moleculesi nt he solid state. In the NDI-PhE ETM, homochiral PhE groups are introduced onto N-substituted groups at each end of the NDI cores.…”

Section: Resultsmentioning

confidence: 99%

“…Small‐molecule charge‐transporting materials have attracted significant attention for application in perovskite solar cells (PSCs), owing to their low‐temperature processability, facile modification, light weight, and mechanical flexibility . In this context, small‐molecule hole‐transporting materials (HTMs) for PSCs, such as arylamine‐based derivatives, have been widely developed . In contrast, only a few classes of electron‐transporting materials (ETMs) based on small molecules have been reported .…”

Section: Introductionmentioning

confidence: 99%

“…[17][18][19][20] In this context, small-molecule hole-transporting materials (HTMs) for PSCs, such as arylamine-based derivatives, have been widely developed. [21][22][23][24][25] In contrast, only af ew classes of electron-transporting materials (ETMs)b ased on small molecules have been reported. [26][27][28][29][30] In anothera pproach, electron transporting layer-free PSCs have been reported.…”

Section: Introductionmentioning

confidence: 99%

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Homochiral Asymmetric‐Shaped Electron‐Transporting Materials for Efficient Non‐Fullerene Perovskite Solar Cells

et al. 2018

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A design strategy is proposed for electron‐transporting materials (ETMs) with homochiral asymmetric‐shaped groups for highly efficient non‐fullerene perovskite solar cells (PSCs). The electron transporting N,N′‐bis[(R)‐1‐phenylethyl]naphthalene‐1,4,5,8‐tetracarboxylic diimide (NDI‐PhE) consists of two asymmetric‐shaped chiral (R)‐1‐phenylethyl (PhE) groups that act as solubilizing groups by reducing molecular symmetry and increasing the free volume. NDI‐PhE exhibits excellent film‐forming ability with high solubility in various organic solvents [about two times higher solubility than the widely used fullerene‐based phenyl‐C61‐butyric acid methyl ester (PCBM) in o‐dichlorobenzene]. NDI‐PhE ETM‐based inverted PSCs exhibit very high power conversion efficiencies (PCE) of up to 20.5 % with an average PCE of 18.74±0.95 %, which are higher than those of PCBM ETM‐based PSCs. The high PCE of NDI‐PhE ETM‐based PSCs may be attributed to good film‐forming abilities and to three‐dimensional isotropic electron transporting capabilities. Therefore, introducing homochiral asymmetric‐shaped groups onto charge‐transporting materials is a good strategy for achieving high device performance.

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Electropolymerized Triphenylamine Network Films for High‐Performance Transparent to Black Electrochromism and Capacitance

Wang

Chen

et al. 2022

Advanced Optical Materials

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can only be called black ECMs. Therefore, in addition to the general electrochromic performance parameters such as contrast ratio, response time, and cyclic stability, for transparent to black ECMs, the satisfactory bleached state is as important as the good black colored state.Conjugated triphenylamine (TPA)based polymers are a kind of potential transparent to black ECMs. [5] TPA cation has strong absorption range of 500-720 nm; [6] N,N,N′,N′-Tetraphenylbenzidine (TPB) is a common bridged structure of polytriphenylamine, its monovalent cation has an absorption in the range of 400-550 and 900-2000 nm, and the absorption of divalent cation is similar to TPA cation covering 550-850 nm range. [7] Both TPA and TPB have no absorption in visible and near-infrared (NIR) regions, hence triphenylamine-based materials may achieve the conversion between transparent and black and NIR electrochromism. [8] Liou and Yen et al. have chemically synthesized a large number of triphenylamine-based materials, [9] including several transparent to black ECMs with outstanding properties. [10] At present, due to the spectral redshift caused by substituents and aggregation, there is still a lack of triphenylamine-based materials with good bleached state, especially low absorption in the range of 400-500 nm.In this work, a precursor, HPB-6TPA, composed entirely of the TPA group was synthesized. Several HPB-6TPA derivatives and substances with similar chemical structures have been reported in the literature, [11] in which electrochemical and spectral properties and potential applications in organic semiconductors have been studied, and the electron transfer and spin states of cationic radicals have been also investigated. The monomer HPB-6TPA was polymerized in situ on an ITO electrode to form a flat polytriphenylamine film by electrodeposition. This film has weak absorption only ranging of 400-425 nm in the visible region; and can realize the conversion of high and low transmittance in the range of 400-2000 nm covering the vis-NIR region, owing to the potential response of TPA and dimeric TPA (TPB) structural units in this TPA network film. The electrochromic performance parameters of this film are impressive. And its specific capacitance is up to 788.9 F g −1 @1.4 A g −1 . In addition, by changing the conditions of EP, films with different contents of electroactive units can be prepared onThe polytriphenylamine films are prepared by electropolymerization from a precursor HPB-6TPA with hexaphenylbenzene (HPB) core bearing six triphenylamine (TPA) units. The abundant and valuable electrochromism from transparent to black and from no to strong near-infrared absorption are achieved from this TPA network film. The presence of residual TPA and dimeric TPA (N,N,N′,N′-tetraphenylbenzidine) units in network film and their independent potential response attain the electrochromic behaviors. The network film possesses short response time and can realize high doping level (72%), attributed to favorable dopant ion channel caused by the twisting struct...

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Molecular “Flower” as the High-Mobility Hole-Transport Material for Perovskite Solar Cells

Cited by 34 publications

References 31 publications

Precise Control of Thermal and Redox Properties of Organic Hole‐Transport Materials

Precise Control of Thermal and Redox Properties of Organic Hole‐Transport Materials

Homochiral Asymmetric‐Shaped Electron‐Transporting Materials for Efficient Non‐Fullerene Perovskite Solar Cells

Electropolymerized Triphenylamine Network Films for High‐Performance Transparent to Black Electrochromism and Capacitance

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