OPTICAL MATERIALS, vol.133, pp.1-14, 2022 (SCI-Expanded)
Transparent, anti-reflective, and electrically compatible contact designs that can effectively be implemented in bifacial applications is attributed as a crucial criterion validated by effective techniques to improve photon harvesting and energy efficiency in high-efficiency CdTe solar cells (SC). As an ITO alternative for CdTe SCs, MoO3/Au/WO3 dielectric/metal/dielectric (DMD) transparent contact is proposed as an effective design in the current study. By integrating the MoO3/Au/WO3 transparent contact into the bifacial CdTe SC, the optimum structural parameters are determined for both top and bottom illumination through light management engineering. An optimal situation is constructed based on the photocurrent density derived from the optical characteristics calculated with the Transfer Matrix Method. The fabricated bifacial CdTe SC with optimal MoO3/Au/WO3 top contact is investigated by comparing with monofacial convectional thick Au top contact and bifacial ITO top contact. In the case of 10 nm metal and 34 nm outer dielectric layer thicknesses (dAu and dWO3, respectively), highest photocurrent density is obtained for both top and top illumination. It has been reported that dAu should be less than 40 nm as the limit of the bifacial operating condition. For the best reflectivity, the following values of dAu = 12 nm and dWO3 = 2540 nm must be taken. For lower and upper illumination, Jsc increases from 17.06 mA/cm2 to 19.91 mA/cm2, and from 5.91 mA/cm2 to 9.27 mA/cm2, respectively. Furthermore, the power conversion efficiency has increased from 9.65% to 10.69% and 3.43 to 4.96 for bottom and top illumination, respectively. Hence, the photon harvesting in CdTe SC with MoO3/Au/WO3 transparent top contact is improved. This superior performance provides a bifaciality from 0.36 to 0.46 by 27.9%. As per the authors’ knowledge, for the first time in the literature, this report introduces the bifacial CdS/CdTe heterojunction-based SC with only MoO3/Au/WO3 DMD transparent top contact via light management engineering. It includes a new methodology and detailed feedback for the design and manufacture of optoelectronic devices that are alternative to ITO due to the bifacial working conditions, that require innovative, anti-reflective and efficient new contact systems, which have been improved with functionally designed DMD integration.