My research interest lies in the area of solar energy conversion via photovoltaic and solar fuel. Here, we are developing a photocathode for hydrogen evolution using metal-sulfide compounds which consisted of earth-abundant materials. Our goal is making photoelectrochemical water splitting a more efficient process with sustainability as the central theme.

Gunawan, W. Septina, T. Harada, Y. Nose, S. Ikeda, “Investigation of the Electric Structures of Heterointerfaces in Pt- and In2S3-Modified CuInS2 Photocathodes Used for Sunlight-Induced Hydrogen Evolution”, ACS Applied Materials and Interfaces 7 (2015) 16086

W. Septina, M. Kurihara, S. Ikeda, Y. Nakajima, T. Hirano, Y. Kawasaki, T. Harada, M. Matsumura, “Cu(In,Ga)(S,Se)₂ thin film solar cell with 10.7 % conversion efficiency obtained by selenization of the Na-doped spray-pyrolyzed sulfide precursor film”, ACS Applied Materials and Interfaces 7 (2015) 6472.

W. Septina, Gunawan, S. Ikeda, T. Harada, M. Matsumura, “Photosplitting of water from wide-gap Cu(In,Ga)S₂ thin films modified with CdS layer and Pt nanoparticles for a high-onset potential photocathode”, Journal of Physical Chemistry C 119 (2015) 8576.

M. Kurihara, W. Septina, S. Ikeda, T. Hirano, Y. Nakajima, Y. Kawasaki, T. Harada, M. Matsumura, “Fabrication of Cu(In,Ga)(S,Se)₂ Thin Film Solar Cells via Spray Pyrolysis of Thiourea and N-Methylthiourea-based Aqueous Precursor Solution”, Japanese Journal of Applied Physics 54 (2015) 091203.

T. H. Nguyen, W. Septina, S. Fujikawa, F. Jiang, T. Harada, S. Ikeda, “Cu2ZnSnS4 Thin Film Solar Cells with 5.8 % of Conversion Efficiency Obtained by a Facile Spray Pyrolysis Technique”, RSC Advances 5 (2015) 77565.

H. K. Adli, , T. Harada, W. Septina, S. Hozan, S. Ito, S. Ikeda, “Effects of Porosity and Amounts of Surface Hydroxyl Groups of a Porous TiO₂ Layer on the Performance of a CH3NH3PbI3 Perovskite Photovoltaic Cell”, Journal of Physical Chemistry C 119 (2015) 22304.

F. Jiang, S. Ikeda, Z. G. Tang, T. Minemoto, W. Septina, T. Harada, M. Matsumura, “Impact of alloying duration of an electrodeposited Cu/Sn/Zn metallic stack on properties of Cu2ZnSnS4 absorbers for thin-film solar cells”, Progress in Photovoltaics: Research and Applications, DOI: 10.1002/pip.2638.

W. Septina, S. Ikeda, Y. Iga, T. Harada, M. Matsumura, “Thin film solar cell based on CuSbS2 absorber fabricated from an electrochemically deposited metal stack”, Thin Solid Films 550 (2014) 700.

S. Ikeda, S. Sogawa, Y. Tokai, W. Septina, T. Harada, M. Matsumura, “Selective production of CuSbS2, Cu3SbS3, and Cu3SbS4 nanoparticles using a hot injection protocol”, RSC Advances 4 (2014) 40969.

Gunawan, W. Septina, S. Ikeda, T. Harada, M. Matsumura, “Platinum and indium sulfide-modified CuInS2 as efficient photocathodes for photoelectrochemical water splitting”, Chemical Communications 50 (2014) 8941.

S. Ikeda, M. Nonogaki, W. Septina, G. Gunawan, T. Harada, W. Septina, “Photoelectrochemical characterizations of CuInS₂ and Cu(In,Ga)S₂ thin films fabricated by a spray pyrolysis method”, Advanced Materials Research 894 (2014) 427.

Y. Lin, S. Ikeda, W. Septina, T. Harada, M. Matsumura, “Mechanistic aspect of preheating effects of electrodeposited metallic precursors on structural and photovoltaic properties of Cu₂ZnSnS₄ thin films”, Solar Energy Materials and Solar Cells 120 (2014) 218.

W. Septina, S. Ikeda, T. Harada, M. Matsumura, “Fabrication of Cu₂ZnSnSe₄ thin films from an electrodeposited Cu‒Zn‒Sn‒Se/Cu‒Sn‒Se bilayer”, physica status solidi (c) 10 (2013) 1062.

S. Ikeda, M. Nonogaki, W. Septina, G. Gunawan, T. Harada, M. Matsumura, “Fabrication of CuInS₂ and Cu(In,Ga)S₂ thin films by a facile spray pyrolysis and their photovoltaic and photoelectrochemical properties”, Catalysis Science and Technology 3 (2013) 1849.

W. Septina, S. Ikeda, A. Kyoraiseki, T. Harada, M. Matsumura, “Single-step electrodeposition of a microcrystalline Cu₂ZnSnSe₄ thin film with a kesterite structure”, Electrochimica Acta 88 (2013) 436.

M. A. Khan, W. Septina, S. Ikeda, M. Matsumura, “An inorganic/organic hybrid solar cell consisting of Cu2O and a fullerene derivative”, Thin Solid Films 526 (2012) 191.

S. M. Lee, S. Ikeda, Y. Otsuka, W. Septina, T. Harada, M. Matsumura, “Homogeneous electrochemical deposition of In on a Cu-covered Mo substrate for fabrication of efficient solar cells with a CuInS₂ photoabsorber”, Electrochimica Acta 79 (2012) 189.

W. Septina, S. Ikeda, M. Alam Khan, T. Harada, M. Matsumura, L. M. Peter, “Potentiostatic electrodeposition of cuprous oxide thin films for photovoltaic applications”, Electrochimica Acta 56 (2011) 4882.

B. Yuliarto, W. Septina, K. Fuadi, F. Fanani, L. Muliani, Nugraha, “Synthesis of nanoporous TiO₂ and its potential applicability for dye-sensitized solar cell using antocyanine black rice”, Advances in Materials Science and Engineering 2010 (2010).