Masafumi Yamaguchi received his B.S. and Ph.D. degrees from Hokkaido University in 1968 and 1978, respectively.

In 1968, he joined the NTT (Nippon Telegraph and Telephone Public Corporation) Electrical Communications Laboratories, where he was engaged in research on radiation damage to semiconductor devices including solar cells, ZnSe blue light emitting diodes using ion implantation and other techniques, molecular beam epitaxy (MBE), heteroepitaxy on Si using metal-organic chemical vapor deposition (MOCVD), III-V compound solar cells and materials, Li batteries, photonic functional devices and their integration working as a Supervisor and a Section Head.

In the field of solar cell research, Dr. Yamaguchi was the first to demonstrate the superior radiation-resistance of InP materials and solar cells, and discovered the light-illumination-enhanced annealing phenomena of radiation damage to InP. His group also developed high-efficiency and radiation-resistant InP cells with efficiencies of 17% at AM0, and showed the great potential of InP cells for space applications in 1984. The first satellite using InP cells (the lunar mission of the Japanese scientific satellite MUSES-A) was launched in early 1990. His group also proposed a double-hetero (DH) structure tunnel junction for realizing a high performance and stable interconnection of multi-junction cell (MJ) cells as one of breakthrough technologies for high-efficiency MJ solar cells, and realized 20.2% AlGaAs/GaAs 2-junction cells in 1987. They developed high-efficiency (20% at AM1.5G) GaAs solar cells fabricated on Si substrates in 1989 and demonstrated space flight experiment using GaAs-on-Si cells in 1994.

In 1994, Dr. Yamaguchi moved to his present position. He has also discovered the superior radiation-resistance of InGaP materials and solar cells, and the light-illumination-enhanced annealing phenomena of radiation damage to InGaP. Discovery of superior radiation-resistance of InP and InGaP, and proposal of DH structure tunnel junction for cell interconnection by his group have contributed to industrialization of InGaP-based MJ space solar cell. He has also contributed to the attainment of high efficiency InGaP/GaAs/InGaAs and InGaP/InGaAs/Ge 3-junction cells with efficiencies of 33.3% (1-sun AM1.5G) in 1997 and 38.9% (500-suns AM1.5) in 2004. 33.3% efficiency still remains 1-sun world-record. He has also contributed to develop high-efficiency InGaP/GaAs/Ge 3-junction concentrator solar cell modules (area of about 7,000cm2 or 5,500cm2 for 400-suns or 550suns use) with an outdoor efficiency of more
than 28.0% in collaboration with Daido Steel, Daido Metal and Sharp Co. in 2003 and shown great potential of concentrator PV for terrestrial application.

Dr. Yamaguchi has been an International Committee (IC) member for the IEEE Photovoltaic Specialists Conference (IEEE-PVSC) since 1988 and has served as a Co-Chair for 25th, from 28th to 31st IEEE-PVSC, an IC member for the European Photovoltaic Solar Energy Conference (EU-PVSEC) since 1994, and that for the International Photovoltaic Science and Engineering Conference (PVSEC) since 1987. He was a Vice General Chairman, Vice Program Chairman and Program Chairman of the 1st, 2nd and 3rd World Conference on Photovoltaic Energy Conversion (WCPEC) in 1994, 1998 and 2003, respectively. In addition, he has proposed International Advisory Committee for the WCPEC in order to organize real international PV conference in 1999. He was also a Chairman of the Next Generation Photovoltaic Power Generation Technologies Research Committee of the Institute of Electrical Engineers of Japan. He is an Editor of the journals “Progress in Photovoltaics” and “Renewable and Sustainable Energy Reviews”.
He made considerable contributions to R&D of photovoltaic technology as a member of the International Energy Agency/Photovoltaic Power System Task II, as a member of the New Sunshine Program Promotion Committee of the Ministry of Economy, International Trade and Industry, and as Chairmen of Super High-Efficiency Solar Cell Committee and High-Efficiency Thin Crystalline Si Solar Cell Committee of the New Energy and Industrial Technology Development Organization (NEDO). He has published more than 250 original journal papers and presented more than 300 International Conferences. He received the Vacuum Science Paper Award of the Vacuum Society of Japan for the study of Si MBE in 1981, the Irving Weinberg Award for contributions to Space Photovoltaics in 1997, the Best Technical Report Award for contribution to Next Generation Photovoltaic Technologies in 2001, Renewable Energy Pioneers Award in 2002 and Becquerel Prize in 2004 for his outstanding contributions to the development of high-efficiency MJ solar cells, and as one of the World leaders of the development of Photovoltaics and as one of the driving forces for international co-operation, as illustrated in the PV World Conferences. He has also received 13 awards for Best Paper Awards and Poster Awards at the PV related international conferences for studies of high-efficiency MJ and concentrator solar cells, and new nitride materials, crystalline Si and new device structure.