Division of Multidisciplinary Chemistry– Molecular Aggregation Analysis –https://www.scl.kyoto-u.ac.jp/~wakamiya/english/index.html

Prof
WAKAMIYA, Atsushi(D Eng)Assist Prof *Senior Lect
Assist Prof
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MURDEY, Richard NAKAMURA, Tomoya TRUONG, Minh Anh
KANEKO, Ryuji(D Eng)(Ph D)(D Eng)(D Eng)*New Research Field
Development ProjectStudents
PD
OHASHI, Noboru(D Eng)PD
PASCUAL MIELGO, Jorge(Ph D)

HU, Shuaifeng (D3)HASHIMOTO, Ruito (D2)
TAN, Tiancheng (D1)TAKEWAKI, Yoshika (M2)
FUNASAKI, Tsukasa (M2)

Researchers (pt)
SHIMAZAKI, Ai

MORISHITA, Taro (M2)
LIU, Wentao (M2)MIYAKE, Yuki (M1)
HARATA, Fuyuki (M1)
HIRA, Shota (M1)

$VVLVW7HFKQ6WD൵
IWASAKI, Yasuko

MATSUSHIGE, Yuko

HARAMATSU, Megumi

Scope of Research
We design and synthesize unique electronic materials with sophisticateddevice applications in mind. These materials have novel solid-state aggregaWLRQVWUXFWXUHVRUZHOOGH¿QHGLQWHUIDFHRULHQWDWLRQWKDWSURPRWHH൶FLHQWHOHFWULFDO FXUUHQW ÀRZ RU HQKDQFH GHYLFH OLIHWLPH (OHFWURQLF GHYLFHV EDVHG RQ
these new materials are then evaluated using advanced measurement techniques, and the results are used to inform the next direction of the materials
chemistry. We call this synergistic approach for achieving our research goals“Needs Inspired Fundamental Science”.

KEYWORDS
Molecular Design and Synthesis

Molecular Aggregation

Functional Materials

Semiconductors

Perovskite Solar Cells

Recent Selected Publications
Hu, S.; Pascual, J.; Liu, W.; Funasaki, T.; Truong, M. A.; Hira, S.; Hashimoto, R.; Morishita, T.; Nakano, K.; Tajima, K.; Murdey, R.; Nakamura,T.; Wakamiya, A., A Universal Surface Treatment for p-i-n Perovskite Solar Cells, ACS Appl. Mater. Interfaces, 14,  Nakamura, T.; Otsuka, K.; Hu, S.; Hashimoto, R.; Morishita, T.; Handa, T.; Yamada, T.; Truong, M. A.; Murdey, R.; Kanemitsu, Y.; Wakamiya,A., Composition-Property Mapping in Bromide-Containing Tin Perovskite Using High-Purity Starting Materials, ACS Appl. Energy Mater., 5,  
Murdey, R.; Ishikura, Y.; Matsushige, Y.; Hu, S.; Pascual, J.; Truong, M. A.; Nakamura, T.; Wakamiya, A., Operational Stability, Low Light
Performance, and Long-Lived Transients in Mixed-Halide Perovskite Solar Cells with a Monolayer-Based Hole Extraction Layer, Sol. Energy
Mater. Sol. Cells, 245,  Hu, S.; Otsuka, K.; Murdey, R.; Nakamura, T.; Truong, M. A.; Yamada, T.; Handa, T.; Matsuda, K.; Nakano, K.; Sato, A.; Marumoto, K.; Tajima,..DQHPLWVX<:DNDPL\D$2SWLPL]HG&DUULHU([WUDFWLRQDW,QWHUIDFHVIRU(൶FLHQW7LQ/HDG3HURYVNLWH6RODU&HOOVEnergy
Environ. Sci., 15,  TOPICS AND INTRODUCTORY COLUMNS OF LABORATORIESTopics
Optimized Carrier Extraction at Interfaces
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Solar Cells&DUULHU H[WUDFWLRQ LQ PL[HG WLQ±OHDG SHURYVNLWH VRODU
cells is improved by modifying the top and bottom perovskite surfaces with ethylenediammonium diiodide andglycine hydrochloride, respectively. Trap densities in theperovskite layers are reduced as a result of surface passivDWLRQH൵HFWVDQGDQLQFUHDVHLQ¿OPFU\VWDOOLQLW\,QDGGLWLRQthe orientated aggregation of the ethylenediammonium andglycinium cations at the charge collection interfaces resultin the formation of surface dipoles, which facilitate charge
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The unencapsulated device also shows improved stability
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strategy is also successfully applied to centimeter-scale deYLFHVZLWKH൶FLHQFLHVXSWR1)

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PHDVXUHGGHYLFHH൶FLHQF\IHOOWHPSRUDULO\GXHWRDWUDQsient loss of output current before returning to the nominal
level after a long recovery period in the dark. These transient
losses were more apparent in the wide bandgap device
under strong light and were likely caused by light-induced
halide segregation. After recovery, both devices retained
good performance under a wide range of light intensities.
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GHYLFHUHDFKHG2)Composition-Property Mapping in BromideContaining Tin Perovskite Using High Purity
Starting Materials
The wide band gaps of bromide-containing tin perovskites, ASnI±[Brx, make them attractive materials foruse as the top-layer absorber in tandem solar cells, as wellas in single junction solar cells for indoor applications. In
the present work, a series of ASnI±[Brx¿OPVZDVV\VWHPatically fabricated by varying the A-site (FA, MA, Cs)and X-site (I±, Br±) ions. The use of solvent-coordinated
SnBr2 complex as a high purity source of bromide combined with Sn(IV) scavenging treatment helps to ensure
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is realized. The energy levels and electronic properties ofWKH¿OPVZHUHFKDUDFWHUL]HGE\SKRWRHPLVVLRQ\LHOGVSHFtroscopy and photoluminescence (PL) measurements. The¿OPV ZLWK ORQJ 3/ OLIHWLPH DQG IDYRUDEOH HQHUJ\ OHYHODOLJQPHQWUHVXOWHGLQVXSHULRUGHYLFHH൶FLHQF\ZKHQHYDOuated in standard single junction solar cells. The best power
FRQYHUVLRQ H൶FLHQF\ RI  ZDV REWDLQHG ZKHQ WKHcomposition was FAMASnI2.25Br.3)

Operational Stability, Low Light Performance,and Long-Lived Transients in Mixed-Halide
Perovskite Solar Cells with a MonolayerBased Hole Extraction Layer
Due to their tunable bandgap and low manufacturingcost, metal halide perovskite solar cells are attractive forDPELHQWLQGRRUOLJKWKDUYHVWLQJDSSOLFDWLRQV,QWKLVZRUN
we evaluate p-i-n perovskite solar cells fabricated withMeO-2PACz, a molecular monolayer hole extraction layer,
as potential candidates for ambient light- harvesting applications. Two triple-cation mixed halide lead perovskite
absorbers are compared, one with high bromide content%U,UDWLREDQGJDSH9SRZHUFRQYHUVLRQH൶FLHQF\  DQG RQH ZLWK ORZ EURPLGH FRQWHQW %U, UDWLREDQGJDSH9SRZHUFRQYHUVLRQH൶FLHQF\ Both materials demonstrated good stability while operating under simulated sunlight at the maximum power point
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Figure 2. Composition-property mapping in bromide -containing tin perovskite using high purity starting materials.

References
1) S. Hu, K. Otsuka, R. Murdey, T. Nakamura, M. A. Truong, T. Yamada,T. Handa, K. Matsuda, K. Nakano, A. Sato, K. Marumoto, K. Tajima, Y.
Kanemitsu, A. Wakamiya, Energy Environ. Sci. 2022, 152) R. Murdey, Y. Ishikura, Y. Matsushige, S. Hu, J. Pascual, M. A. Truong,T. Nakamura, A. Wakamiya, Sol. Energy Mater. Sol. Cells 2022, 245,
3) T. Nakamura, K. Otsuka, S. Hu, R. Hashimoto, T. Morishita, T. Handa,T. Yamada, M. A. Truong, R. Murdey, Y. Kanemitsu, A. Wakamiya, ACS
Appl. Energy Mater. 2022LQSUHVV '2,DFVDHPF ICR ANNUAL REPORT, 2022

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