DOI： 10.35848/1347-4065/ae3c21

Web of Science

出版者・発行元：Ees Solar  

Inverted perovskite solar cells (PSCs) with planar p–i–n architecture offer enhanced stability and tandem compatibility. However, their performance remains constrained by the instability and rigidity of conventional metal cathodes. Single-walled carbon nanotubes (SWCNTs) have emerged as promising alternatives owing to their conductivity, flexibility, and processability. However, their intrinsic p-type nature and low work function relative to the perovskite conduction band limit their applicability as cathodes in PSCs. To overcome these challenges, we employed a molecular doping strategy using planar aromatic n-type dopants, to modulate the electronic properties of SWCNTs. Three π-conjugated imide-based molecules N,N′-bis[3-(dimethylamino)propyl]perylene-3,4,9,10-tetracarboxylic diimide (PDIN), its bay-substituted dibromo derivative, N,N′-bis[3-(dimethylamino)-propyl]-1,7-dibromoperylene-3,4,9,10-tetracarboxyl diimide (PDINBr<inf>2</inf>), and the naphthalene analogue N,N′-bis[3-(dimethylamino)propyl]naphthalene-1,4,5,8-tetracarboxylic diimide (NDIN) were selected for their tunable LUMO levels, high intrinsic conductivity, and strong π–π interactions with SWCNTs. Density functional theory (DFT) calculations reveal that PDINBr<inf>2</inf> doped SWCNTs exhibited the formation of new unoccupied states favorable for efficient charge transfer from the electron transporting layer (ETL), supported by stable adsorption and strong orbital overlap. The doped SWCNTs were integrated as cathodes in inverted PSCs, achieving power conversion efficiencies up to 10.12%. Device characterization confirmed improved electron extraction, extended carrier lifetime, and suppressed interfacial recombination. Moreover, perylene-based dopants contributed to enhanced device stability, with unencapsulated cells retaining 80% of their initial efficiency after 800 hours under ambient light and 25% relative humidity. This work demonstrates a new strategy to use planar aromatic molecular dopants for enabling SWCNTs as cathodes and provides a pathway for scalable, metal-free electrodes in next-generation PSCs.

DOI： 10.1039/d5el00171d

Open Access

Scopus

記述言語：英語   出版者・発行元：Nanomaterials  

The advancement of efficient and stable perovskite solar cells (PSCs) increasingly depends on developing flexible, metal-free electrode architectures. Single-walled carbon nanotubes (SWCNTs) offer chemical robustness, high conductivity, and mechanical flexibility, making them promising candidates to replace brittle metal cathodes. However, pristine SWCNTs are intrinsically p-type, creating energy barriers and recombination losses in inverted (p–i–n) PSCs. Achieving stable n-type doping compatible with both SWCNTs and perovskites is therefore critical. Here, seven representative n-type dopants, small molecules (TBD and TPP), ionic salts (TBAI, TBABr, and B18C6·KCl), and polymers (PEI and PVP) were systematically investigated to elucidate their effects on doping efficiency and interfacial stability. Morphological, structural, and electronic analyses supported by DFT calculations reveal that strong bases and ionic dopants promote perovskite degradation, whereas polymeric and coordination-type dopants preserve crystallinity and surface uniformity. Among them, PEI- and TPP-doped SWCNT electrodes achieved the best device performance, with power conversion efficiencies of 9.6% and 8.1%, respectively, demonstrating efficient electron extraction and interfacial stability. These findings highlight that interfacial chemical compatibility rather than intrinsic donor strength governs the effectiveness of n-type SWCNT doping, providing rational design principles for stable, metal-free perovskite photovoltaics.

DOI： 10.3390/nano16010064

Web of Science

Scopus

PubMed

出版者・発行元：Journal of Materials Chemistry A  

Single-walled carbon nanotubes (SWCNTs) typically possess p-type semiconducting properties when exposed to air and oxygen, making them commonly used as anodes in perovskite solar cell (PSC) devices. In this study, we proposed a facile n-type doping strategy to enable SWCNTs to function as cathodes in inverted (p–i–n) PSCs [glass/indium tin oxide/poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)/MAPbI<inf>3</inf>/n-doped SWCNT:PCBM]. Organophosphorus compounds, including triphenylphosphine (TPP), 1,2-bis(diphenylphosphino)ethane (DPPE), and 1,1′-bis(diphenylphosphino)ferrocene (DPPF), were utilized as molecular n-type dopants for SWCNT electrodes. The doping mechanisms and their application in PSCs were validated through computational and experimental studies. Overcoating doped SWCNTs with PCBM was found to be essential to remove uncoordinated dopants, enhancing surface contact with the perovskite layer and maintaining n-type characteristics. This process mitigated energy mismatches caused by shallow LUMO levels of phosphine-based dopants, thereby improving electron transport and optimizing energy levels for efficient charge transfer. Inverted PSCs incorporating DPPE-doped SWCNT electrodes demonstrated significant improvements in device efficiency, increasing from 5.1% to 8.03%. From the carrier lifetime studies, these improvements are attributed to rapid electron transfer and reduced recombination at the interface between the doped SWCNTs and the bulk perovskite. Notably, the n-type dopants that induced significant energy level shifts adversely affected the PSC performance. The hydrophobic nature of the doped electrodes contributed to the long-term stability of the devices. Unencapsulated PSCs with doped electrodes retained 50% of their initial efficiency after 500 h of storage under controlled humidity (25% RH), temperature (25 °C), and ambient light (300 lux) conditions.

DOI： 10.1039/d5ta06786c

Web of Science

Scopus

記述言語：英語   出版者・発行元：ACS Applied Materials and Interfaces  

4-(1,3-Dimethyl-2,3-dihydro-1H-benzimidazol-2-yl)-N,N-dimethylaniline (N-DMBI) was employed as an n-dopant for single-walled carbon nanotube (SWCNT) thin films, enabling the fabrication of an inverted perovskite solar cell with the structure ITO/hole transport layer (HTL)/CH<inf>3</inf> NH<inf>3</inf> PbI<inf>3</inf> /6,6-phenyl-C61-butyric acid methyl ester (PCBM)/N,N’-bis[3-(dimethylamino)propyl]perylene-3,4,9,10-tetracarboxylic diimide (PDIN)/N-DMBI-doped SWCNT. This structure eliminates the need for conventional metallic back electrodes. When poly(3,4-ethylenedioxythiophene) polystyrenesulfonate (PEDOT:PSS) was used as HTL, a power conversion efficiency of 9.9% was achieved. Substituting PEDOT:PSS with poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) further improved the PCE to 10.1%. The long-term stability of the device was evaluated under a nitrogen atmosphere for 50 days. The PCE of devices with Ag electrodes decreased by 50%, whereas those with SWCNT electrodes retained 90% of their initial performance. N-DMBI doping of SWCNT thin films reduced the sheet resistance from 73.4 Ω/sq to 32.6 Ω/sq and shifted the ionization potential to a shallower value. Furthermore, the Seebeck coefficient changed from +65.7 μV/K to −22.5 μV/K, confirming the successful formation of n-type SWCNTs. X-ray photoelectron spectroscopy revealed that doping with N-DMBI or PDIN effectively removed oxygen and water molecules from the SWCNT surface. This study introduced PDIN as an interfacial layer between PCBM and the SWCNTs, preventing direct contact between these layers. This structure exhibited J–V characteristics with reduced losses in open-circuit voltage and fill factor by suppressing carrier traps.

DOI： 10.1021/acsami.5c18054

Web of Science

Scopus

PubMed

総ページ数：194   担当ページ：27-35   記述言語：日本語 著書種別：学術書

担当区分：筆頭著者   記述言語：日本語   掲載種別：記事・総説・解説・論説等（商業誌、新聞、ウェブメディア）  

記述言語：日本語   掲載種別：記事・総説・解説・論説等（商業誌、新聞、ウェブメディア）  

記述言語：英語  

記述言語：英語   掲載種別：研究発表ペーパー・要旨（国際会議）  

記述言語：英語   掲載種別：研究発表ペーパー・要旨（国際会議）  

開催年月日： 2026年3月

記述言語：日本語   会議種別：口頭発表（招待・特別）  

開催地：東京大学先端科学技術研究センター3号館2階セミナー室   国名：日本国  

開催年月日： 2026年3月

記述言語：英語   会議種別：ポスター発表  

開催地：Nagoya University   国名：日本国  

開催年月日： 2025年12月

記述言語：英語   会議種別：口頭発表（招待・特別）  

開催地：Nagoya University   国名：日本国  

開催年月日： 2025年12月

記述言語：日本語   会議種別：口頭発表（招待・特別）  

開催地：あいちウインク   国名：日本国  

開催年月日： 2025年10月

記述言語：日本語   会議種別：ポスター発表  

開催地：三重県伊勢市宇治中之切町152   国名：日本国  

発表場所：名古屋大学