Emergent Supramolecular Materials Research Team

Principal Investigator

PI Name Yong-Jin Pu
Degree D.Eng.
Title Team Leader
Brief Resume
2002D. Eng., Waseda University
2002Research associate, Waseda University
2004JSPS Postdoctoral Fellowship for Research Abroad
2006Research associate, Yamagata University
2010Associate Professor, Yamagata University
2013PRESTO Researcher, Japan Science and Technology Agency
2017Team Leader, Emergent Supramolecular Materials Research Team, Supramolecular Chemistry Division, RIKEN Center for Emergent Matter Science (-present)


We have developed the multi-layered photon-electron conversion devices in which an organic semiconductor layer was deposited on an inorganic semiconductor layer, or vice versa. Chemical or electrical junction at the interface between organic and inorganic layers largely affects performance of the devices. Such a junction is originally based on intermolecular interaction or chemical reaction, and the active control of the interaction at the molecular level is necessary. Our challenge is to synthesize the molecular hybrids of organic and inorganic semiconductors and develop their new functions. Especially, we develop novel photocatalysts or molecular sensors by the 2D- or 3D-controlled molecular hybridized network. We also challenge to create the macroscopic function switching device, triggered by the dynamic change of the network in non-equilibrium state.

Research Fields

Chemistry, Materials Science


Organic/inorganic molecular hybrid
Molecular network
Semiconductor nanoparticle
2D materials
Dynamic control


One dimensional self-assembly of colloidal quantum dots

Colloidal quantum dots (QDs) in assembled state are expected to exhibit unique photoelectronic properties that single QD does not exhibit. Two or three dimensionally ordered assembly of the QDs have been reported so far. However, the QD has almost isotropic spherical shape, and therefore, it is extremely difficult to achieve one dimensional self-assembly of the QDs.

We achieved the 1D self-assembly of colloidal QDs on PbSO4 nanoribbons by a selective adsorption process in hydrophobic media. The assembly pattern was either a straight line or two straight lines, and these patterns were selectively controlled. The densely packed 1D self-assembly of colloidal QDs into a straight line pattern, without the use of a molecular bridge or adhesive would be fascinating for realizing quantum resonance 1D QD structures


One-dimensionally self-assembled colloidal QDs: left) PbS QDs (9.3 nm) and right) CdS QDs (4.0 nm).


Molecules creating two electron-hole pairs from one photon

Singlet fission is one of multiexciton generation processes that one singlet exciton converts into two triplet excitons through an intermediate of two neighboring molecules. If the generated triplet excitons can dissociate into free charges at the donor/acceptor interface, it may provide a way to dramatically improve photon-electron conversion efficiency of photovoltaics. Singlet fission requires molecules to satisfy the energy condition of E(S1) ≥ 2 E(T1) and dense molecular packing, and those molecules have been limited to polycyclic π-conjugated compounds such as pentacene and tetracene.

We developed the thienoquinoid-based non-polycyclic singlet fission molecules by the modulation of the biradicaloid character of the molecules and the consequent controlling E(T1) of the molecules. The photocurrent response of thienoquinoid-based devices is largely dependent on LUMO level of an acceptor, and it was demonstrated that the triplet excitons dissociated into charges. We believe that these singlet fission molecules represent a new expansion for the molecular design of multiexciton generation materials and will lead to development of novel photon-electron conversion devices based on management of excited state and spin multiplicity.


A thienoquinoid-based singlet fission molecule and photocurrent spectra (left) and energy diagram of singlet fission and charge separation of triplet excitons.


Yong-Jin Pu

Team Leader

Minjun Kim

Postdoctoral Researcher

Jianjun Liu

Postdoctoral Researcher

Seokhoon Jang

Postdoctoral Researcher


  1. T. Lee, K. Enomoto, K. Ohshiro, D. Inoue, T. Kikitsu, H.-D. Kim, Y.-J. Pu, D. Kim

    Controlling the dimension of the quantum resonance in CdTe quantum dot superlattices fabricated via layer-by-layer assembly

    Nat. Commun. 11, 5471 (2020)
  2. N. Aizawa, Y. Harabuchi, S. Maeda, and Y.-J. Pu

    Kinetic prediction of reverse intersystem crossing in organic donor-acceptor molecules

    Nat. Commun. 11, 3909 (2020)
  3. Y.-J. Pu, Y. Koyama, D. Otsuki, M. Kim, H. Chubachi, Y. Seino, K. Enomoto, and N. Aizawa

    Exciplex emissions derived from exceptionally long-distance donor and acceptor molecules

    Chem. Sci. 10, 9203 (2019)
  4. K. Enomoto, D. Inoue, and Y. J. Pu

    Controllable 1D Patterned Assembly of Colloidal Quantum Dots on PbSO4 Nanoribbons

    Adv. Funct. Mater. 29, 1905175 (2019)
  5. Y.-J. Pu, R. Satake, Y. Koyama, T. Otomo, R. Hayashi, N. Haruta, H. Katagiri, D. Otsuki, D. Kim, and T. Sato

    Absence of delayed fluorescence and triplet-triplet annihilation in organic light emitting diodes with spatially orthogonal bianthracenes

    J. Mater. Chem. C 7, 2541 (2019)



2-1 Hirosawa, Wako, Saitama 351-0198 Japan