Study on the Strain Dependent Performance of CdTe:Te-based Multijunction Solar Cells

CdTe:Te-based multijunction solar cells (MJSCs) show great promise in recent years due to its unique material properties with band gap tunability. There is a mismatch between experimental efficiency of these devices with the published modeling data. This work focuses on the development of a model considering the strain issue and its effects on the performance of CdTe:Te-based MJSCs. Using multi-layered strain model, strain phenomenon is determined for three kinds of MJSC structures named as MJSC-1, MJSC-2 and MJSC-3. The results are described in terms of typical subcell thickness of 80nm, 100nm and 120nm, and the number of subcells of 3, 5 and 7. Noticeably, the Matlab simulations reveals that the magnitude of MJSC position-dependent strain is strongly dependent on the subcell thickness and it is decreased with increasing the layer thickness. It is also observed that the position-dependent strain increases with increasing the number of subcells. First, the MSJC efficiencies for all structures are evaluated and found lower compared to that reported without taking into account of strain. The reduction of efficiency is identified due to the modification of the open circuit voltage and short circuit current under tensile strain condition. An efficiency of the MJSC-3 for seven-layers structure is 35.39% is found and this is up to 2.8303% less when no strain effect is taken into account. The efficiency of MJSC-1 for seven-layer is found to be the highest (36.32%) among all the considered strain conditions strain conditions. Reduction of the layers also produced lessen of the efficiencies.