Thin film solar cells

are considered the next generation of solar cells and are expected to be considerably

cheaper because they need much less material and energy in their production

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than today’s photovoltaic modules.

Researchers around the globe are racing to develop efficient thin film solar

cells. The solar cells made in Luxembourg are based on a semiconductor made

of copper, indium, gallium and selenium (CIGS) and made by a process with the

potential for highest performance. Furthermore, the scientists of the University

of Luxembourg produced another solar cell based on a new cheaper material, which

does not contain the costly indium, and made by a low cost galvanic process.

This solar cell has reached an efficiency of 3.2 percent. This is already close

to the world record: the worldwide best cell based on this new material and

prepared by a similar low cost process shows an efficiency of 3.4 percent.

The laboratory for photovoltaics of the University of Luxembourg is a group

of researchers developing new materials and processes for solar cells. Of all

the available thin film technologies, solar cells based on CIGS have shown the

highest efficiencies in research and in production. Prof Susanne Siebentritt,

head of the laboratory, explains: “Currently we can produce the heart of

the solar cells, the so called absorber layer and the buffer. But for completing

the solar cells we rely on the help of our colleagues from Helmholtz-Zentrum

Berlin”. The luxembourgish laboratory focuses not only on the development

of solar cells but also on furthering the physical understanding of the materials

and interfaces involved in these solar cells.

The laboratory for photovoltaics (LPV) was founded in April 2007 within the

framework of the TDK Europe professorship, a public-private partnership funded

by TDK corporation and the University of Luxembourg. “We have just a few

months ago moved into our new labs. This allows us finally to start the solar

cell preparation. These are really our first solar cells and they have already

reached competitive efficiencies”, Prof Siebentritt says, “I am very

proud of my team”.