Monocrystalline CdTe solar cell with ultra-high open-circuit voltage and substantially increased efficiency

We report the demonstration of CdTe/MgxCd1-xTe double heterostructures (DHs) with a carrier lifetime of 3.6 μs and an interface recommendation velocity of 1.2 cm/s, comparable to or even better than the best values reported for GaAs/Al0.5Ga0.5As (18 cm/s) and GaAs/Ga0.5In0.5P (1.5 cm/s) DHs. Combined with a p-contact layer (8 nm a-SiCy:H + 4 nm a-Si:H), devices consisting of MgxCd1-xTe/CdTe/Mg0.24Cd0.76Te DHs have demonstrated an efficiency of 14.66% ± 1.4% with a Voc of 0.9954 V ± 0.3% certified by NREL. The maximum certified Voc is 1.0542 V ± 0.5%. Additional measurements reveal that the best tested device has a Voc of 1.036 V, a Jsc of 22.3 mA/cm, a fill-factor of 73.6%, and a power conversion efficiency of 17.0%. The maximum Voc measured from these devices is 1.096 V. All these device characteristics are substantially greater than the previous records for Voc (0.892 V) and efficiency (13.4%).