A High-Quality Dopant-Free Electron-Selective Passivating Contact Made from Ultra-Low Concentration Water Solution

Abstract

Crystalline silicon solar cells produced by doping processes have intrinsic shortages of high Auger recombination and/or severe parasitic optical absorption. Dopant-free carrier-selective contacts (DF-CSCs) are alternative routines for the next generation of highly efficient solar cells. However, it is difficult to achieve both good passivating and low contact resistivity for most DF-CSCs. In this paper, a high-quality dopant-free electron-selective passivating contact made from ultra-low concentration water solution is reported. Both low recombination current (J0) ~10 fA/cm2 and low contact resistivity (ρc) ~31 mΩ·cm2 are demonstrated with this novel contact on intrinsic amorphous silicon thin film passivated n-Si. The electron selectivity is attributed to relieving of the interfacial Fermi level pinning because of dielectric properties (decaying of the metal-induced gap states (MIGS)). The full-area implementation of the novel passivating contact shows 20.4% efficiency on a prototype solar cell without an advanced lithography process. Our findings offer a very simple, cost-effective, and efficient solution for future semiconductor devices, including photovoltaics and thin-film transistors.

Stable Dopant-Free Electron-Selective Contact for Silicon Solar Cells

“…TiO x , TiN x , CdS, In 2 S 3 , Cs 2 CO 3 , LiF x , CsF x , MgF x , EuF 3 , CeF x , GdF x , PEI, and Triton X-100 are dopant-free electron-selective contacts (DF-ESCs). − These DF-ESCs show adequate carrier selectivity without delicate and harsh doping and can be easily fabricated using straightforward low-temperature procedures such as atomic layer deposition (ALD), spin-coating process, thermal evaporation, and magnetron sputtering. The exploration of DF-CSCs for solar cells gained momentum in 2016 with the achievement of a 19.42% efficiency in a heterojunction solar cell featuring an “a-Si:H­(i)/MoO 3 /ITO front stack layer and a rear a-Si:H­(i)/LiF x /Al configuration” .…”