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

Abstract

In this study, the front work function WFITO 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, Sint) structure and ITO/(p)a-Si:H/(i1)a-Si:H/(i2)a-Si:H/(n)a-Si:H/metal (double intrinsic, Dint) structure, fabricated using RF-PECVD method were simulated, using AFORS-HET (Automated FOR Simulation of Heterostructures) software. Based on these simulations, the work functions (WFITO) value ought to range from 4.9 to 5.7 eV, in order to determine the optimum WFITO 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 Dint structure’s external parameters (e.g., VOC,JSC, FF, Eff) are higher, compared to the Sint structure. Furthermore, the absorber (i1 and i2) layers bandgap is optimized in an effort to improve the Dint solar cell’s performance. According to the results, the Dint structure had a 10.76 % maximum efficiency (VOC = 969.8 mV, JSC = 16.03 mA/cm2, and FF = 70 %), using WFITO, i1 layer bandgap, and i2 layer bandgap of 5.7 eV, 1.82 eV, and 1.86 eV, respectively.

Keywords

• WFITO
• RF-PECVD
• AFORS-HET
• a-Si:H
• bandgap
• absorber layers