Effects of LiF/Al back electrode on the amorphous/crystalline silicon heterojunction solar cells

To improve the quantum efficiency (QE) and hence the efficiency of the amorphous/crystalline silicon heterojunction solar cell, we have employed a LiF dielectric layer on the rear side. The high dipole moment of the LiF reduces the aluminum electrode's work function and then lowers the energy barrier at back contact. This lower energy barrier height helps to enhance both the operating voltage and the QE at longer wavelength region, in turn improves the open-circuit voltage (V-oc), short-circuit current density (J(sc)), and then overall cell efficiency. With optimized LiF layer thickness of 20 nm, 1 cm(2) heterojunction with intrinsic thin layer (HIT) solar cells were produced with industry-compatible process, yielding V-oc of 690 mV, J(sc) of 33.62 mA/cm(2), and cell efficiencies of 17.13%. Therefore LiF/Al electrode on rear side is proposed as an alternate back electrode for high efficiency HIT solar cells. (C) 2012 Elsevier B.V. All rights reserved.