Design of Grating Al2O3 Passivation Structure Optimized for High-Efficiency Cu(In,Ga)Se2 Solar Cells

Abstract

In this paper, we propose an optimized structure of thin Cu(In,Ga)Se2 (CIGS) solar cells with a grating aluminum oxide (Al2O3) passivation layer (GAPL) providing nano-sized contact openings in order to improve power conversion efficiency using optoelectrical simulations. Al2O3 is used as a rear surface passivation material to reduce carrier recombination and improve reflectivity at a rear surface for high efficiency in thin CIGS solar cells. To realize high efficiency for thin CIGS solar cells, the optimized structure was designed by manipulating two structural factors: the contact opening width (COW) and the pitch of the GAPL. Compared with an unpassivated thin CIGS solar cell, the efficiency was improved up to 20.38% when the pitch of the GAPL was 7.5–12.5 μm. Furthermore, the efficiency was improved as the COW of the GAPL was decreased. The maximum efficiency value occurred when the COW was 100 nm because of the effective carrier recombination inhibition and high reflectivity of the Al2O3 insulator passivation with local contacts. These results indicate that the designed structure has optimized structural points for high-efficiency thin CIGS solar cells. Therefore, the photovoltaic (PV) generator and sensor designers can achieve the higher performance of photosensitive thin CIGS solar cells by considering these results.

Potential of Iron Oxides in Photovoltaic Technology

“…143 Al 2 O 3 is also usually used as a passivation layer in CIGS and Si-based solar cells. 144,145 It was reported that Fe 2 O 3 intended to serve as an ETL could also play the passivation layer role in perovskite solar cells. The Fe 2 O 3 ETL layer in the form of nanoparticles having network morphology could improve the cell performance induced by the passivation effect of interface defects and thus generated a high UV stability.…”

“…Various metal oxides were found suitable to serve as a passivation layer in many solar cell devices. , For instance, organic solar cells with triethanolamine-passivated ZnO exhibited a very minimum trap density and thus increased electron mobility and induced longer times in charge carrier recombination lifetime; consequently, the PCE improved . Al 2 O 3 is also usually used as a passivation layer in CIGS and Si-based solar cells. , It was reported that Fe 2 O 3 intended to serve as an ETL could also play the passivation layer role in perovskite solar cells. The Fe 2 O 3 ETL layer in the form of nanoparticles having network morphology could improve the cell performance induced by the passivation effect of interface defects and thus generated a high UV stability …”

SiOx Patterned Based Substrates Implemented in Cu(In,Ga)Se2 Ultrathin Solar Cells: Optimum Thickness

“…On the other hand, the EM wave interaction with the line contact architecture promotes changes in the electric field distribution, since the periodic line grating will influence the interference pattern, disrupting the previously seen planar behavior. In this case, at 1036 nm the presence of a HPS promotes for a destructive interference that increases with increased SiO2 thickness, as more light is reflected with the thicker layer [54]. An optical optimization of the HPS architecture is required in order to shift the destructive interference away from the solar spectrum region of interest (> 1100 nm).…”

Ray Tracer Simulation of Si-Based Solar Cells using Al2O3/ITO as Double Layers Anti Reflective Coating

“…The average reflectance of a TJ solar cell is decreased from 25.57 to 3.37 % thanks to TLAR coating, which has a stronger antireflection effect in the wavelength range of 300 -1,800 nm than TiO2/Al2O3 DLAR coating [17]. Using optoelectrical simulations, Wang improved the structure of thin Cu(In,Ga)Se2 (CIGS) solar cells with a grating aluminium oxide (Al2O3) passivation layer (GAPL) offering nano-sized contact holes [18]. The efficient carrier recombination inhibition and high reflectivity of the Al2O3 insulator passivation with local contacts caused the efficiency value to peak at 100 nm for the contact opening width [18].…”

“…Using optoelectrical simulations, Wang improved the structure of thin Cu(In,Ga)Se2 (CIGS) solar cells with a grating aluminium oxide (Al2O3) passivation layer (GAPL) offering nano-sized contact holes [18]. The efficient carrier recombination inhibition and high reflectivity of the Al2O3 insulator passivation with local contacts caused the efficiency value to peak at 100 nm for the contact opening width [18].…”