Fundamental limit of nanophotonic light trapping in solar cells.
Establishing the fundamental limit of nanophotonic light-trapping schemes is of paramount importance and is becoming increasingly urgent for current solar cell research. The standard theory of light trapping demonstrated that absorption enhancement in a medium cannot exceed a factor of 4n(2)/sin(2)θ, where n is the refractive index of the active layer, and θ is the angle of the emission cone in the medium surrounding the cell. This theory, however, is not applicable in the nanophotonic regime. Here we develop a statistical temporal coupled-mode theory of light trapping based on a rigorous electromagnetic approach. Our theory reveals that the conventional limit can be substantially surpassed when optical modes exhibit deep-subwavelength-scale field confinement, opening new avenues for highly efficient next-generation solar cells.
Yu
Zongfu
Z
Ginzton Laboratory, Stanford University, Stanford, CA 94305, USA. zfyu@stanford.edu
Raman
Aaswath
A
Fan
Shanhui
S
D000042:Absorption; D004738:Engineering / Q000379:methods*; D008027:Light; D008962:Models, Theoretical; D049329:Nanostructures / Q000737:chemistry*; D012993:Solar Energy / Q000706:statistics & numerical data*