Modelling and performance analysis of amorphous silicon solar cell using wide band gap nc‐Si:H window layer

Abstract

Poor charge transport mechanism and light-induced degradation effects are among the key factors leading to the degraded performance of single-junction amorphous silicon (a-Si:H) solar cells. Existent photovoltaic configurations, based on amorphous silicon carbide (a-SiC:H) window layer, have established efficiencies in the range of 7-10%. Limited performance of such devices has been addressed by replacing a-SiC:H with a wide band gap (∼2 eV) hydrogenated nano-crystalline silicon (nc-Si:H) layer that reportedly exhibits crystalline properties at small scale. Here, the proposed solar cell based on p-nc-Si:H/i-a-Si:H (buffer)/i-a-Si:H/n-a-Si:H configuration has been simulated with SILVACO TCAD by analysing window and intrinsic absorber layers thickness, as well as doping concentrations. Along with the engineering of p/i interface, in-depth evaluation of absorber defects parameters has also been undertaken in order to reduce the recombination rate. The simulated results of an optimised single-junction device demonstrated an open-circuit voltage (VOC) of 0.865 V, short-circuit current density (JSC) of 21.7 mA/ cm 2 , Fill factor (FF) of 0.69 and power conversion efficiency of 12.93%, which is promising when compared with the solar cell already reported. The proposed structure will provide the platform for further development of low cost and efficient multijunction thin-film amorphous solar cell technology.

The Effects of Dopant Concentration on the Performances of the a-SiOx:H(p)/a-Si:H(i1)/a-Si:H(i2)/µc-Si:H(n) Heterojunction Solar Cell

“…Moreover, when the dopant concentration was raised to 1.0 x 10 21 cm -3 , the overlystrong electric field of 3.48 x 10 6 Vcm -1 generated a higher defect density at the p/i interface. This served as both recombination and trapping centres for charge carriers (Mehmood and Tauqeer, 2017). These results were confirmed by calculating the trapped hole densities for 3 NA dopant concentrations, as shown in Fig.…”

The Development of Carbon/Silicon Heterojunction Solar Cells through Interface Passivation

“…In most cases, researchers employed an architecture resembling that of an organic solar cell with a window or frame‐like geometry defined in the middle of a Si wafer. [ 41 ] In this geometry, a SiO 2 /Si wafer was etched to reveal a small silicon opening in the SiO 2 and the surrounding SiO 2 was coated with metal electrode (such as Au, Ag, or Pt/Ti). The use of a window or frame like geometry allowed for the carbon film to be processed separately and later transferred to the window and this design was successful for many years.…”

Dopant‐free passivating contacts for crystalline silicon solar cells: Progress and prospects

“…However, despite the good passivation quality, the parasitic absorption of a ‐Si:H( i ) is inevitable due to its narrow band gap, and its poor thermal stability limits the preparation process of solar cells. Alternative Si‐based hydrogen‐rich materials with wider band gap have instead been utilized in SHJ solar cells, such as a ‐SiO x :H, 184 μc ‐Si:H, 185 and a ‐SiC x :H 186 . The wider band gap of these materials cuts down the parasitic light absorption of a ‐Si:H in the short wavelength of the solar spectrum, endowing them with great potential as the passivation layer in dopant‐free passivating contact c ‐Si solar cells.…”