Dresden 2011 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 39: Photovoltaics: Chalcopyrites I

HL 39.7: Talk

Tuesday, March 15, 2011, 15:00–15:15, FOE Anorg

Luminescence investigation of Cu(In,Ga)Se₂solar cells with different Ga-contents grown in a three-stage-process on glass substrate — •Kristin Wendt¹, Mathias Müller¹, Thomas Hempel¹, Frank Bertram¹, Jürgen Christen¹, Daniel Abou-Ras², Thorsten Rissom², Thomas Unold², and Hans-Werner Schock² — ¹Institute of Experimental Physics, Otto-von-Guericke-University Magdeburg, Germany — ²Helmholtz-Zentrum Berlin for Materials and Energy, Germany

A fundamental advantage of Cu(In,Ga)Se₂ (CIGS) alloys as absorber materials in thin-film solar cells is their direct band gap energies which can be varied between 1.04 eV (CuInSe₂) and 1.68 eV (CuGaSe₂). Photoluminescence (PL) spectra of complete CIGS solar cells with a systematic variation of the Ga-content in the absorber layer will be presented. The CIGS cells investigated were grown on a Mo back contact sputtered on soda lime glass and have a Ga-concentration ranging over the entire range from CuInSe₂ to CuGaSe₂. Samples with Ga-contents between 100 % and 33 % show two broad luminescence bands. In contrast, CuInSe₂ exhibits only one broad luminescence band. Each band is composed of two or three different transitions. Varying excitation density over four orders of magnitude results for samples with Ga-content of 0 % and 33 % in a blueshift of the main peak with increasing excitation density. For higher Ga-concentrations, first a blue- and then a redshift of the dominating peak with increasing excitation density is visible. The temperature dependence of the PL spectra is investigated going from 4 K to 300 K.