Ga-doping of MZO in CdSeTe/CdTe thin film solar cells

Metastable effects in high efficiency MZO/CdSeTe/CdTe solar cells have been studied in an attempt to recover the device performance. Devices with the MZO buffer layer have shown an 'S' shaped behaviour in the J-V characteristics before any preconditioning. This is removed after light soaking under 1000 Wm^-2 at 25 °C. However, this recovery remained only for a short period of time while the devices were stored under vacuum in the dark. Recent studies with Ga doping of the buffer MZO has shown the removal of this metastability in the J-V characteristics of CdTe devices can be achieved without light soaking. A significant improvement in conductivity and Hall signal has been measured with Ga doped MZO layers compared to previously measured MZO films. However, a gradual decrease in the Hall signal has been observed over time after films were light soaked and removed from the desiccator.