The influences of the front work function and intrinsic bilayer (i₁, i₂) on p-i-n based amorphous silicon solar cell’s performances: A numerical study

In this study, the front work function WF_ITO and absorber layer bandgap’s influences on two solar cells structure performances, namely ITO/(p)a-Si:H/(i)a-Si:H/(n)a-Si:H/metal (single intrinsic, S_int) structure and ITO/(p)a-Si:H/(i₁)a-Si:H/(i₂)a-Si:H/(n)a-Si:H/metal (double intrinsic, D_int) structure, fabricated using RF-PECVD method were simulated, using AFORS-HET (Automated FOR Simulation of Heterostructures) software. Based on these simulations, the work functions (WF_ITO) value ought to range from 4.9 to 5.7 eV, in order to determine the optimum WF_ITO for high solar cell efficiency, confirmed with the J-V dark characteristic, the band diagram in thermodynamics equilibrium, build-in electric field distribution, trapped holes density, as well as the quantum efficiency. The simulation results showed the D_int structure’s external parameters (e.g., V_OC,J_SC, FF, E_ff) are higher, compared to the S_int structure. Furthermore, the absorber (i₁ and i₂) layers bandgap is optimized in an effort to improve the D_int solar cell’s performance. According to the results, the D_int structure had a 10.76 % maximum efficiency (V_OC  = 969.8 mV, J_SC  = 16.03 mA/cm², and FF = 70 %), using WF_ITO, i₁ layer bandgap, and i₂ layer bandgap of 5.7 eV, 1.82 eV, and 1.86 eV, respectively.