CdTe thin-film solar cells with cobalt-phthalocyanine back contacts

We have fabricated CdTe thin-film solar cells using cobalt-phthalocyanine (CoPC) and Au as Cu-free back contacts on F-doped SnO2-coated soda lime glass substrates. The CdTe solar cells using CoPC/Au back contacts showed 80–120 mV improvements on open circuit voltage (VOC) as compared to the cells using Au-only back contacts. The best small area cell using CoPC/Au back contacts has demonstrated an efficiency of 14.3% with an open circuit voltage of 815 mV, a short circuit current of 24.3 mA/cm2, and a fill factor of 72.3% under AM1.5 illumination. Accelerated life testing performed at 200 °C and open circuit biasing revealed degradations, partially caused by the presence of oxygen and/or moisture.