1. Towards sustainable photovoltaics: the search for new materials by L. M. Peter Philosophical Transactions A Volume 369(1942):1840-1856 May 13, 2011 ©2011 by The Royal Society

2. Occurrence in the Earth’s crust and current costs of some of the elements relevant to thin-film photovoltaics. L. M. Peter Phil. Trans. R. Soc. A 2011;369:1840-1856 ©2011 by The Royal Society

3. Annual production of some of the elements relevant for photovoltaics. L. M. Peter Phil. Trans. R. Soc. A 2011;369:1840-1856 ©2011 by The Royal Society

4. Yearly sum of global irradiation in Europe (adapted from [4])—see also http://re.jrc.ec.europa.eu/pvgis/. L. M. Peter Phil. Trans. R. Soc. A 2011;369:1840-1856 ©2011 by The Royal Society

5. Total installed world PV capacity (ROW, rest of the world) [6]. L. M. Peter Phil. Trans. R. Soc. A 2011;369:1840-1856 ©2011 by The Royal Society

6. Maximum theoretical efficiency (Shockley–Queisser limit) for solar cells under AM1.5 illumination without concentration. L. M. Peter Phil. Trans. R. Soc. A 2011;369:1840-1856 ©2011 by The Royal Society

7. Best research solar cell efficiencies. L. M. Peter Phil. Trans. R. Soc. A 2011;369:1840-1856 ©2011 by The Royal Society

8. Cross-sectional diagram of the structure of a typical CdS|CdTe solar cell. L. M. Peter Phil. Trans. R. Soc. A 2011;369:1840-1856 ©2011 by The Royal Society

9. Cross-sectional diagram of the structure of a typical CIGS solar cell. L. M. Peter Phil. Trans. R. Soc. A 2011;369:1840-1856 ©2011 by The Royal Society

10. Schematic diagram to illustrate the electrochemical and electronic processes taking place in a dye-sensitized solar cell under operating conditions. L. M. Peter Phil. Trans. R. Soc. A 2011;369:1840-1856 ©2011 by The Royal Society

11. Structure of an organic bulk heterojunction solar cell. L. M. Peter Phil. Trans. R. Soc. A 2011;369:1840-1856 ©2011 by The Royal Society

12. Life cycle of a PV array used to calculate the energy payback time (EPT, years) and CO2 emission rate (g C kW h−1). L. M. Peter Phil. Trans. R. Soc. A 2011;369:1840-1856 ©2011 by The Royal Society

13. Breakdown of EPT for three PV technologies based on data given by Wild-Schoten [27]. L. M. Peter Phil. Trans. R. Soc. A 2011;369:1840-1856 ©2011 by The Royal Society

14. Section of the periodic table showing the logic of changing from CuIn(Ga)Se2 to Cu2ZnScS4 by moving from group 13 to groups 12 and 14. L. M. Peter Phil. Trans. R. Soc. A 2011;369:1840-1856 ©2011 by The Royal Society

15. Crystal structure of copper zinc tin sulphide (CZTS), which is a promising sustainable alternative to CIGS [31]. L. M. Peter Phil. Trans. R. Soc. A 2011;369:1840-1856 ©2011 by The Royal Society