Reduction in electron lifetime induced by excess electrons was a key effect in degradation of solar cells based on boron-doped and oxygen-containing silicon. Although boron related, degradation was controlled by the concentration of holes and not by the boron concentration. This recent finding was the basis for a new degradation model in which the degradation starts from a latent complex BiO2 of an interstitial boron atom and an oxygen dimer. Electron-induced reconstruction of this defect results in a production of recombination centers. This model provided a detailed explanation of the basic features of the degradation, and of subsequent recovery by annealing in the dark.

Latent Complexes of Interstitial Boron and Oxygen Dimers as a Reason for Degradation of Silicon-Based Solar Cells. V.V.Voronkov, R.Falster: Journal of Applied Physics, 2010, 107[5], 053509