Electroluminescence mapping of CuGaSe_2 solar cells by atomic force microscopy

摘要

The authors report on the observation of electroluminescence (EL) in CuGaSe_2 solar cells using tapping-mode atomic force microscopy based on tuning-fork sensors. Individually injected current pulses are seen during intermittent contact driven by an external bias applied to the conducting tip. It follows that EL can be stimulated when the solar cell is forward biased during the contact cycle. Local L-V characteristics show evidence for EL, with a threshold voltage of 3.0-3.7 V. Mapping of the photon emission suggests that grain boundaries effectively isolate grain interiors, which behave as individual light-emitting diodes.