P-type multilayer graphene as a highly efficient transparent conducting electrode in silicon heterojunction solar cells

In this paper, we have simulated the structure of a p-graphene/n-crystalline silicon solar cell by using AFORS-HET software. Following our recent report (Patel and Tyagi, AIP Adv. 5 (2015) 077165) here also we have considered graphene as 3D in nature. To obtain confinement, boundary conditions have been applied by controlling number of layers. Formation of Schottky junction has been ensured by making of electrical contact along the c-axis to collect the minority carriers. Power conversion efficiency of 6.75 % has been achieved with best-simulated cell's parameters of p-type single layer graphene. Under the illumination conditions of AM1.5G, it has been observed that as layer number increases up to 20 efficiency decreases linearly to 4.34 %. Through the optimization of parameters of n-crystalline silicon layer, a maximum efficiency of 9.812 % has been achieved for 80 μm thick silicon. Such heterojunction photovoltaic device has shown large temperature dependence. Cell performance has been further tested taking parameters of commercial available n-type Si. Optimum efficiency of 11.47 % has been achieved for 100 μm thick silicon layer. Finally, we have demonstrated that p-type multilayer graphene can act as an efficient transparent conducting electrode.

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