Graded Bandgap Ultrathin CIGS Solar Cells (Invited Paper)

In this paper, we physically modeled passivated ultrathin Cu (In1-xGax) Se-2 solar cells with different bandgap grading configurations. Firstly, we have designed the cell architecture according to the fabricated model. The novelty in this work is the modeling of passivated u-CIGS solar cells with different bandgap grading profile configurations in order to achieve high efficiency with a thickness of 500 nm. A significant influence on device performance has been observed while changing absorber doping density, electron affinity, and operating temperature (range of 10-70 degrees C) for the investigated samples. ZnS has been used as a buffer layer to replace the conventional CdS material in order to improve cell efficiency. The impact of the buffer doping density and electron affinity on u-CIGS cell performance is explored. The simulation results show that a high bandgap at the front and rear sides with an acceptor density of 2 x 10(16) provide the best electrical cell parameters: J(sc) of 31.53 mA/cm(2), V-oc of 742.78 mV, FF of 77.50%, eta of 18.15%. Our findings can be considered guidelines for new single and/or tandem cell optimization to achieve high efficiency.

Automated summary

In this paper, passivated ultrathin Cu (In1-xGax)Se2 solar cells with different bandgap grading configurations were physically modeled. The impact of absorber doping density, electron affinity, and operating temperature on device performance was observed. ZnS was used as a buffer layer to replace CdS and improve cell efficiency. Simulation results showed that a high bandgap at the front and rear sides with an acceptor density of 2 x 10^(16) provided the best electrical cell parameters: J(sc) of 31.53 mA/cm^2, V-oc of 742.78 mV, FF of 77.50%, eta of 18.15%. These findings can guide the optimization of new single and/or tandem cells for high efficiency.