Double-Barrier Quantum-Well Structure: An Innovative Universal Approach for Passivation Contact for Heterojunction Solar Cells

Abstract

The main drawbacks of modern solar-cell technologies are low-quality surface passivation, recombination losses, and carrier selectivity, which limit their efficiency. Therefore, this study proposes an innovative universal approach for a doublebarrier two-dimensional (2D) quantum well (QW) passivation structure for solar cells. To this end, c-Si solar cells were examined as model cells. Preliminary investigations (e.g., contact resistance, passivation, and recombination current density) were conducted with a stack of SiO x /nc-Si/SiO x QW on n-type surfaces, and excellent results were obtained with a 30 nm-thick nc-SiO x (n) carrier-selective layer. Furthermore, the effects of different QW thicknesses and doping doses on the surface passivation of such contacts were studied, and the best results were achieved for a 5 nm QW. These QWs also exhibited a low degree of dopant diffusion, which was suppressed by the double SiO x layer. Furthermore, the 2D QW passivation structure with carrier-selective layers, which was denoted as a heterojunction with quantum well (HQW) solar cell, exhibited an excellent passivation improvement and had a lifetime (τ eff ) of 2746 μs and an implied open-circuit voltage (iV oc ) of 736 mV for a 5 nm 2D QW structure. Moreover, a fabricated 5 nm 2D QW-based silicon heterojunction (SHJ) solar cell exhibited an open-circuit voltage (V oc ) of 732.5 mV, a short-circuit current density (J sc ) of 39.5 mA/cm 2 , a fill factor (FF) of 77.95%, and an efficiency (E ff ) of 22.55%. To validate these findings, theoretical calculations were performed using the experimental results, which confirmed the resonance tunneling of charge carriers across the 5 nm HWQ structure.

Novel Passivation and Gettering Strategy for Silicon Wafer by Al2O3/n‐poly‐Si/SiOx Stack for High‐Efficiency p‐Type Passivating Tunnel Oxide Contact Solar Cells

“…[27] Since then, tremendous progress has been carried out, culminating in the implementation of the PERL architecture, which attained a record-breaking efficiency of 25%. [28] In recent years, there is growing attention in solar cells with passivating contacts, that consist of an interface oxide in combination with a deposited silicon layer doped with pentavalent element (for n-type) or trivalent element (for p-type), [29,30] which is commonly known as passivating tunnel oxide contact (TOPCon). [31] The advantages associated with TOPCon solar cells encompass several key aspects, which include: 1) compatibility with DOI: 10.1002/ente.202301031…”

“…[ 27 ] Since then, tremendous progress has been carried out, culminating in the implementation of the PERL architecture, which attained a record‐breaking efficiency of 25%. [ 28 ] In recent years, there is growing attention in solar cells with passivating contacts, that consist of an interface oxide in combination with a deposited silicon layer doped with pentavalent element (for n‐type) or trivalent element (for p‐type), [ 29,30 ] which is commonly known as passivating tunnel oxide contact (TOPCon). [ 31 ] The advantages associated with TOPCon solar cells encompass several key aspects, which include: 1) compatibility with well‐established PERC production lines, allowing for the utilization of existing high‐temperature firing processes for metal contact formation as well as front passivation and antireflection coating procedures; 2) incorporation of a full area tunneling contact, enabling enhanced fill factor (FF) by eliminating lateral carrier transport; 3) elimination of the need for laser opening by simplifying the manufacturing process; and 4) wide process flexibility and versatility with less constraints on the deposition of a‐Si:H precursor layer achievable through techniques such as low‐pressure chemical vapor deposition, [ 32–35 ] plasma‐enhanced chemical vapor deposition (PECVD), [ 36–44 ] and sputtering.…”

New value of old knowledge: sulphur-based GaAs surface passivation and potential GaAs application in molecular electronics and spintronics

“…Many attempts have been made for more than two decades to deactivate the high surface density of states using several elements and compounds. Presently surface passivation topic is quite active in GaAs-related solar cells [15,[33][34][35][36][37], but without any discovery of a permanent solution to the active surface problem [2,38]. Sulfur (S) passivation has been the most promising surface treatment, significantly improving surface electrical properties and drawing considerable attention [39][40][41][42][43][44][45].…”