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 Sciences


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


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


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