Stringing Monolithic Three Terminal III-V Tandems

Abstract

Tandemdevicesarewellknowntosurpasssinglejunctions.However,thelimitationsofcurrent-matchingisaconcern for changing spectra in terrestrial applications. Three terminal tandem (3T) devices can be more robust to these variations resulting in higher energy yield than single junction devices and two terminal series-connected tandems. We fabricate one-sun 3T tandem devices made of inverted grown III-V tandem (GaInP/t/GaAs) as a prototype of 3T tandems for stringing and measurement demon- strations. We demonstrate 3T tandem measurements that can be used to understand the use of 3T tandems in various constrained configurations. We have demonstrated the improvement of unconstrained 3T tandem cells over 2T series-connected cells as the illumination changes. We present initial results for micro-module with up to 8 3T tandem devices to be strung together.