Simulation of a Charged Al2O3 Film As An Assisting Passivation Layer For a-Si Passivated Contact p-Type Silicon Solar Cells

Abstract

In this paper, a charged Al2O3 tunneling film as an assisting for amorphous Si (a-Si) passivated contact layer is proposed and theoretically simulated for its potential application in improving a-Si passivated contact p-type (a-PC-p) solar cell. The concept is based on an Ag/n+ c-Si/p c-Si/Al2O3/p+ a-Si/Al structure. The key feature is the introduction of a charged Al2O3 layer, which facilitates the tunneling of holes through an Al2O3 insulator layer accompanied by the reduction of interface defect density (Dit). The negative charge in the Al2O3 layer makes the energy band of p-type c-Si bend upward, realizing the accumulation of holes and repelling of electrons at the c-Si/a-Si interface simultaneously. The influence of interface negative charges (Qit) between a-Si and c-Si, Al2O3 thickness, Al2O3 bandgap, interface defect density (Dit) at the a-Si/c-Si interface are systematically investigated on the output parameters of a-PC-p cells. Inserting a charged Al2O3 film between the c-Si/a-Si interface, a +4.2 % relative efficiency gain is predicted theoretically compared with the a-PC-p cells without the Al2O3 layer. Subsequently, the device performance under various temperatures is simulated, and the insertion of a charged Al2O3 layer obviously decreases the Pmax temperature coefficient from -0.336 % /℃ to -0.247 % /℃, which is analogous to that of Heterojunction with Intrinsic Thin layer (HIT) solar cell. The above results demonstrate a better temperature response for a-PC-p cells with a charged Al2O3 layer, paving a road for its potential application in high-efficiency and high thermal stability a-PC-p solar cells.

Numerical Design of Ultrathin Hydrogenated Amorphous Silicon-Based Solar Cell

“…Generally, the performance of solar cells is dependent on three main factors: material selection, material growth technique, and device architecture [18]. A solar cell consists of a semiconductor material that absorbs light and then generates excess electrons and holes [15]. Figure 1 is the structure of a-Si:H-based solar cells.…”

“…In this approach, this can be numerically modelled through the rate of reflection at the rear contact and the absorption coefficient of the active layer (i) of the a-Si:Hbased solar cell in the SCAPS-1D software. As is known to all, the device quality is mainly determined by factors including emitter quality and interface quality [15]. In order to validate our solar cell model, we start from a comparative study of the J-V characteristic of the results of the experiment and simulation, and on the other hand, we study the influence of the various parameters (thickness, bulk defects density, and properties of buffer layer/absorber interface) on the performance of the solar cell, using SCAPS-1D software.…”

“…Defect states at the interface of two layers can cause strong interface recombination in solar cell. A low interface state in the midgap can be achieved by the insertion of intrinsic hydrogenated amorphous silicon in the a-Si/c-Si passivated contact (a-PC) solar cell[15]. Modelling and optimizing a solar cell require controlling the interface states between the…”