WO2007107452-A1  KAWANO K ET AL: &quot;Application of rare-earth complexes for photovoltaic precursors&quot; SOLAR ENERGY MATERIALS AND SOLAR CELLS, ELSEVIER SCIENCE PUBLISHERS, AMSTERDAM, NL, vol. 48, no. 1-4, November 1997 (1997-11), pages 35-41, XP004111830 ISSN: 0927-0248;  XIE R-J ET AL: &quot;PREPARATION AND LUMINESCENCE SPECTRA OF CALCIUM- AND RARE-EARTH (R = EU, TB, AND PR)-CODOPED ALPHA-SIALON CERAMICS&quot; JOURNAL OF THE AMERICAN CERAMIC SOCIETY, BLACKWELL PUBLISHING, MALDEN, MA, US, vol. 85, no. 5, 1 October 2000 (2000-10-01), pages 1229-1234, XP001151981 ISSN: 0002-7820;  DIAW D: &quot;Effect of ion-implanted Eu +3 on the conversion efficiency of amorphous silicon solar cell&quot; SOLAR ENERGY MATERIALS AND SOLAR CELLS, ELSEVIER SCIENCE PUBLISHERS, AMSTERDAM, NL, vol. 53, no. 3-4, June 1998 (1998-06), pages 379-383, XP004148864 ISSN: 0927-0248 cited in the application;  DIAW D: &quot;Effect of ion-implanted Eub *+3b + on the conversion efficiency of amorphous silicon solar cell&quot; SOLAR ENERGY MATERIALS AND SOLAR CELLS, ELSEVIER SCIENCE PUBLISHERS, AMSTERDAM, NL, vol. 53, no. 3-4, June 1998 (1998-06), pages 379-383, XP004148864 ISSN: 0927-0248 cited in the applicationEP1999799-B1  DIAW D: &quot;Effect of ion-implanted Eu +3 on the conversion efficiency of amorphous silicon solar cell&quot; SOLAR ENERGY MATERIALS AND SOLAR CELLS, ELSEVIER SCIENCE PUBLISHERS, AMSTERDAM, NL, vol. 53, no. 3-4, June 1998 (1998-06), pages 379-383, XP004148864 ISSN: 0927-0248 cited in the application;  KAWANO K ET AL: &quot;Application of rare-earth complexes for photovoltaic precursors&quot; SOLAR ENERGY MATERIALS AND SOLAR CELLS, ELSEVIER SCIENCE PUBLISHERS, AMSTERDAM, NL, vol. 48, no. 1-4, November 1997 (1997-11), pages 35-41, XP004111830 ISSN: 0927-0248;  XIE R-J ET AL: &quot;PREPARATION AND LUMINESCENCE SPECTRA OF CALCIUM- AND RARE-EARTH (R = EU, TB, AND PR)-CODOPED ALPHA-SIALON CERAMICS&quot; JOURNAL OF THE AMERICAN CERAMIC SOCIETY, BLACKWELL PUBLISHING, MALDEN, MA, US, vol. 85, no. 5, 1 October 2000 (2000-10-01), pages 1229-1234, XP001151981 ISSN: 0002-7820