High‐Performance Transparent Electron‐Selective Contact for Crystalline Silicon Solar Cells

Abstract High‐efficiency silicon solar cells featuring doped silicon layer‐based carrier‐selective contacts suffer from optical losses due to parasitic absorption. In this work, a high‐performance electron‐selective contact with high transparency is presented, consisting of intrinsic hydrogenated amorphous silicon (a‐Si:H) passivation layer, atomic‐layer‐deposited conductive magnesium oxide (MgO_x) and low‐work‐function aluminium doped zinc oxide (AZO). The a‐Si:H/MgO_x/AZO stack is demonstrated to be an excellent and transparent electron‐selective contact on c‐Si, featuring a small contact resistivity (ρ_c) of 56.0 mΩ cm² and a low saturation current density (J₀) of 2.9 fA cm⁻² simultaneously. By the implementation of the a‐Si:H/MgO_x/AZO front contact, a high power conversion efficiency (PCE) of 23.3% is achieved on silicon heterojunction (SHJ) solar cells, featuring an absolute short‐circuit current density (J_sc) and PCE gain of 1.3 mA cm⁻² and 1.2%, respectively, compared to the conventional phosphorus‐doped silicon layer‐based electron‐selective contact. Moreover, a state‐of‐the‐art PCE of 22.8% is obtained on c‐Si solar cells with dopant‐free asymmetric heterocontacts on both sides, featuring an a‐Si:H/MgO_x/AZO front contact and an a‐Si:H/vanadium oxide (VO_x) rear contact.