The effect of shunt resistance on External Quantum Efficiency measurements at high light bias conditions

Series connection of multi-junction devices can lead to opto-electronic interactions between junctions and thus coupling effects. These effects can be important during External Quantum Efficiency (EQE) measurements of multi-junction devices. In an attempt to find the impact of coupling effects on different shunt resistance devices, EQE measurements have been carried out at high intensity light bias conditions. These measurements showed that in those conditions, the coupling current in high quality materials is considerably higher compared to low quality ones and lead to a higher reduction of the EQE signal. The difference in EQE is, nevertheless, small and it is apparent in all the response region of the material.