Structure and IV characterization diagram of solar cells.
In silicon heterojunction (SHJ) solar cells, thinning the hydrogenated microcrystalline silicon hole layer (uc-Si:H(p+)) reduces its parasitic absorption and increases the short-circuit current density (J
sc), but deteriorates passivation, significantly lowering the open-circuit voltage (V
oc) and fill factor (FF), thus limiting efficiency. This work proposes and validates an ultrathin nanocrystalline silicon/molybdenum oxide (uc-Si:H(p+)/MoOx) bilayer hole transport structure that effectively resolves this tradeoff. The ultrathin uc-Si:H(p+) layer within the bilayer minimizes sputtering damage from MoOx deposition and provides a degree of carrier selectivity. The MoOx layer enhances cell passivation by blocking indium diffusion from the transparent conductive oxides (TCO) into the uc-Si:H(i) layer and passivating dangling bonds at the uc-Si:H(p+) surface, thereby boosting V
oc. Furthermore, due to its high work function, large conduction band offset, and small valence band offset, MoOx reduces carrier recombination and improves hole extraction and transport, consequently increasing J
sc and FF. The champion cell achieved a V
oc of 0.72 V, J
sc of 40.10 mA/cm2, FF of 78.42%, and power conversion efficiency (PCE) of 22.72%, surpassing the performance of the initial cell with an unthinned uc-Si:H(p+) layer (V
oc 0.72 V, J
sc 38.89 mA/cm2, FF 78.10%, PCE 21.82%).
Solar RRL, EarlyView. Read More
