New thin-film solar cells may enable solar-cell technology to maintain its 50% annual growth during the past five years.

Candidate materials to replace today’s amorphous silicon include cadmium telluride, CIGS (copper indium gallium diselenide), and dyes painted onto the surface of nanometer-size particles of titanium dioxide.

In sunny climates, the technology is expected to lead to “grid parity” — electricity generated by photovoltaics as cheaply as it is sold by utilities — within four years or so.