Carbon-chain length substituent effects on Cu(II) phthalocyanines as dopant-free hole-transport materials for perovskite solar cells

Feng, Yaomiao; Chen, Qian; Dong, Lei; Zhang, Zihao; Li, Chen; Yang, Songhe; Cai, Siyuan; Xu, Zong‐Xiang

doi:10.1016/j.solener.2019.04.019

Cited by 19 publications

(13 citation statements)

References 48 publications

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“…Moreover, the synthesis cost of DTPC13‐ThTPA was evaluated to be $14.36 per gram. In this report, the longer branched alkyl chain lead to, not only a larger HOMO energy level in films, but also a smoother film surface and higher hole mobility, which is in good accordance with previous attempts …”

Section: Organic Hole Transporting Materialssupporting

confidence: 93%

Development of Dopant‐Free Organic Hole Transporting Materials for Perovskite Solar Cells

Pham

Yang

Jain

et al. 2020

Advanced Energy Materials

229

170

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There has been considerable progress over the last decade in development of the perovskite solar cells (PSCs), with reported performances now surpassing 25.2% power conversion efficiency. Both long‐term stability and component costs of PSCs remain to be addressed by the research community, using hole transporting materials (HTMs) such as 2,2′,7,7′‐tetrakis(N,N′‐di‐pmethoxyphenylamino)‐9,9′‐spirbiuorene(Spiro‐OMeTAD) and poly[bis(4‐phenyl)(2,4,6‐trimethylphenyl)amine] (PTAA). HTMs are essential for high‐performance PSC devices. Although effective, these materials require a relatively high degree of doping with additives to improve charge mobility and interlayer/substrate compatibility, introducing doping‐induced stability issues with these HTMs, and further, additional costs and experimental complexity associated with using these doped materials. This article reviews dopant‐free organic HTMs for PSCs, outlining reports of structures with promising properties toward achieving low‐cost, effective, and scalable materials for devices with long‐term stability. It summarizes recent literature reports on non‐doped, alternative, and more stable HTMs used in PSCs as essential components for high‐efficiency cells, categorizing HTMs as reported for different PSC architectures in addition to use of dopant‐free small molecular and polymeric HTMs. Finally, an outlook and critical assessment of dopant‐free organic HTMs toward commercial application and insight into the development of stable PSC devices is provided.

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Section: Organic Hole Transporting Materialssupporting

confidence: 93%

Development of Dopant‐Free Organic Hole Transporting Materials for Perovskite Solar Cells

Pham

Yang

Jain

et al. 2020

Advanced Energy Materials

229

170

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“…Besides the above example that demonstrates the importance of side chains attached on the arms, sidechains directly on the Pc cores were also reported, such as butyl, [140] methyl, [143] and hexyl sulfanyl groups. [144] Xu et al [143] developed a six-methyl and one-butyl-modified ZnPc molecule termed Me 6 Bu-ZnPc with a control molecule H 6 Bu-ZnPc which bore only one butyl sidechain.…”

Section: Pc Coresmentioning

confidence: 81%

“…Although dopant-free SM-HTMs based on Pc cores were successfully applied in PSCs previously, [160][161][162][163] the solutionprocessed molecules began to reach a PCE of over 15% just in 2019. [137][138][139][140][142][143][144] In order to benefit describing the evolution of all the Pc-based HTMs, the molecules with TPA or DPA arms are also included in this part. Subsequently, we divide the SM-HTMs based on Pc cores into three classes, one with TPA or DPA arms, [139,142] one with aromatic arms other than TPA or DPA, [137,138] and one with alkyl, alkoxyl, or alkyl sulfanyl sidechains.…”

Section: Pc Coresmentioning

confidence: 99%

“…Subsequently, we divide the SM-HTMs based on Pc cores into three classes, one with TPA or DPA arms, [139,142] one with aromatic arms other than TPA or DPA, [137,138] and one with alkyl, alkoxyl, or alkyl sulfanyl sidechains. [140,143,144] Due to the widely reported success of using TPA or DPA to construct SM-HTMs, TPA arms were also picked to modify the periphery of Pc cores, though very few highly efficient SM-HTMs were reported. Muccini et al [139] conducted a research on such a molecule named OMe-TPA-CuPc with a control…”

Section: Pc Coresmentioning

confidence: 99%

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A Review on Solution‐Processable Dopant‐Free Small Molecules as Hole‐Transporting Materials for Efficient Perovskite Solar Cells

et al. 2020

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Perovskite solar cells (PSCs) based on conventional hole‐transporting materials (HTMs) have achieved power conversion efficiencies comparable to those of typical inorganic solar cells; however, the dopants used to increase the hole mobility or the film‐forming ability impart these devices with a poor long‐term stability, blocking the industrial commercialization of PSCs. As an alternative, HTMs without any dopants are explored. Herein, dopant‐free small molecular HTMs (SM‐HTMs) are reviewed and the performance based on the analyses of their molecular structures are evaluated. A summary of the designing principle and an outlook of the development of highly efficient SM‐HTMs are presented.

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“…Moreover, severe morphology defects, such as pinholes, are typically observed due to the migration and redistribution of noncovalently bonded dopants. , These instability issues must be overcome for the commercialization of PSCs. Therefore, to replace Spiro-OMeTAD , dopant-free HTMs, including small organic molecules, − metal complexes, − conjugated polymers, − and inorganic compounds, − have been explored and applied in PSCs. − Small organic molecular, large 2D planar π-stacked type, and long π-conjugated donor−π–acceptor type compounds , are well-known as HTMs. The development of dopant-free spiro-type HTMs has also been undertaken eagerly.…”

Section: Introductionmentioning

confidence: 99%

Highly Efficient Dopant-Free Cyano-Substituted Spiro-Type Hole-Transporting Materials for Perovskite Solar Cells

Onozawa-Komatsuzaki

Tsuchiya

Inoue

et al. 2022

ACS Appl. Energy Mater.

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The hole-transporting material (HTM) is an important component of perovskite solar cells (PSCs) because it plays a crucial role in achieving high performance. The most frequently used HTM is 2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylamino)-9,9′-spirobifluorene (Spiro-OMeTAD). Spiro-OMeTAD requires dopants such as Li(TFSI) to realize high power conversion efficiencies (PCEs). However, these dopants cause severe instability issues in PSCs. The Spiro-OMeTAD layer also tends to undergo severe morphological deformation at high temperature, which produces large voids and further reduces the cell performance. These drawbacks must be overcome for the commercialization of PSCs. Therefore, it is strongly desirable to develop high-performance dopant-free HTMs to replace Spiro-OMeTAD. Here, we synthesize two cyano-substituted spirobifluorene-based HTMs, SF27 and SF48, for this purpose. These compounds are derived from Spiro-N, which is a Spiro-OMeTAD analogue obtained via the replacement of the p-methoxy substituents with strong electron-donating p-N,N-dimethylamino groups. The influence of cyano substituents on the optoelectronic properties, PCEs, and charge transport behavior in PSCs are investigated. These compounds have a highest occupied molecular orbital energy level that is well-matched to the valence band of perovskite layers. The hole mobility of SF48 (o-cyano-substituted) was determined to be higher than that of SF27 (m-cyano-substituted), although it is lower than those of Spiro-OMeTAD and the reference compound Spiro-N. Mesoporous PSCs were fabricated using these new HTMs without dopants under relatively low HTM concentration conditions, and the cell performance was compared to that of devices with Spiro-OMeTAD and Spiro-N. The PSC with non-doped SF48 exhibited a high PCE of 18.7%, which is comparable to that of the reference PSCs with doped Spiro-OMeTAD (18.6%). In addition, the thermal stability of SF48 at 85 °C in air was superior to that of Spiro-OMeTAD, both with and without dopants. Therefore, the SF48 spirobifluorene-based compound is determined to be quite effective as a high-performance dopant-free HTM for PSCs.

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Carbon-chain length substituent effects on Cu(II) phthalocyanines as dopant-free hole-transport materials for perovskite solar cells

Cited by 19 publications

References 48 publications

Development of Dopant‐Free Organic Hole Transporting Materials for Perovskite Solar Cells

Development of Dopant‐Free Organic Hole Transporting Materials for Perovskite Solar Cells

A Review on Solution‐Processable Dopant‐Free Small Molecules as Hole‐Transporting Materials for Efficient Perovskite Solar Cells

Highly Efficient Dopant-Free Cyano-Substituted Spiro-Type Hole-Transporting Materials for Perovskite Solar Cells

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