Cu(In, Ga)Se ₂ Thin Films on Flexible Polyimide Sheet: Structural and Electrical Properties versus Composition

Abstract

The structural and electrical properties of Cu(In,Ga)Se2 (CIGS) films grown on polyimide (PI) sheet using the three-stage co-evaporation process are investigated by x-ray diffraction spectra (XRD), scanning electron microscopy (SEM), Raman spectra, and Hall effect measurements, respectively. The results show that the properties of CIGS films on PI sheet are strongly dependent on the compositional ratio of Cu/(In+Ga) (Cu/III). In contrast to the non-stoichiometric CIGS films, stoichiometric CIGS films show better structural and electrical properties, such as a relatively larger grain size, lower resistivity and higher carrier concentration. The flexible CIGS solar cells on PI sheet with the conversion efficiencies of 9.7% and 6.6% are demonstrated for the CIGS absorber layer with Cu/III of 0.96 and 0.76, respectively (active area, 0.20 cm 2 ). The cell efficiency for Cu-poor CIGS films is limited by a relatively lower open circuit voltage and fill factor.

Investigation of CIGS Solar Cells on Polyethylene Terephthalate Substrates

“…The advantages of lightweight, effective, flexible and robust (unbreakable) modules are evident, especially with regard to novel applications [4][5][6].…”

Development of Manufacturing CIGS Thin Film Solar Cells Deposited on Polyimide

“…CIGS grain was smaller and the concentration of carrier was lower and there was high resistivity (In 0.68 Ga 0.32 ) 2 Se 3 phase in low temperature compared with in high temperature were discovered [17]. The further study revealed the composition ratio of Cu/(In+Ga) results in the (In 0.68 Ga 0.32 ) 2 Se 3 phase [18]. There were high resistivity (In 0.68 Ga 0.32 ) 2 Se 3 phase in the poor-Cu CIGS thin film and low resistivity Cu x Se, thus, the efficiency of CIGS thin film is 6.6% and 9.7% respectively.…”