Buried‐Metal‐Grid Electrodes for Efficient Parallel‐Connected Perovskite Solar Cells

The limited conductivity of existing transparent conducting oxide (TCO) greatly restricts the further performance improvement of perovskite solar cells (PSCs), especially for large‐area devices. Herein, buried‐metal‐grid tin‐doped indium oxide (BMG ITO) electrodes are developed to minimize the power loss caused by the undesirable high sheet resistance of TCOs. By burying 140‐nm‐thick metal grids into ITO using a photolithography technique, the sheet resistance of ITO is reduced from 15.0 to 2.7 Ω sq−1. The metal step of BMG over ITO has a huge impact on the charge carrier transport in PSCs. The PSCs using BMG ITO with a low metal step deliver power conversion efficiencies (PCEs) significantly better than that of their counterparts with higher metal steps. Moreover, compared with the pristine ITO‐based PSCs, the BMG ITO‐based PSCs show a smaller PCE decrease when scaling up the active area of devices. The parallel‐connected large‐area PSCs with an active area of 102.8 mm2 reach a PCE of 22.5%. The BMG ITO electrodes are also compatible with the fabrication of inverted‐structure PSCs and organic solar cells. The work demonstrates the great efficacy of improving the conductivity of TCO by BMG and opens up a promising avenue for constructing highly efficient large‐area PSCs. The unfavorable conductivity of existing transparent conducting oxide electrodes restricts the development of large‐area perovskite solar cells. Herein, buried‐metal‐grid tin‐doped indium oxide electrodes are developed based on a photolithography technique. Such electrodes with greatly enhanced conductivity and low‐height metal steps help increase device performance and mitigate performance loss while upscaling cell area.