Dark current characteristics of InAs/GaNAs strain-compensated quantum dot solar cells

In order to control the position of quasi-Fermi level for the intermediate quantum energy states of a quantum dot solar cell (QD SC), direct impurity doping into QDs is an effective method. In this work, we have investigated the dark current characteristics of InAs/GaNAs strain-compensated QD SCs fabricated with and without direct doping of InAs QDs with Si. The introduction of Si-doped active QD region into SC significantly reduces Shockley–Read–Hall (SRH) recombination rates and the effect of doping on dark current characteristics has been demonstrated by both numerical simulation and experiments. The dark current measured for direct Si-doped QD SC was reduced by a factor of larger than 2 compared to non-doped QD SC in the bias range of V=0–0.5 V.

► We investigated the diode characteristics of InAs/GaNAs strain-compensated QD SCs. ► Effect of doping was demonstrated by both calculation and experiments. ► Introduction of a Si-doped QD region into SC reduces SRH recombination rates. ► Dark current of direct Si-doped QD SC was more than halved compared to non-doped.