Stable Electron-Selective Contacts for Crystalline Silicon Solar Cells Enabling Efficiency over 21.6%

Abstract

Crystalline silicon (c-Si) solar cells featuring carrier-selective passivating contacts have become a prominent path to develop highly efficient photovoltaic devices. Development of electron-selective materials that can provide excellent surface passivation and low contact resistivity to c-Si substrates while presenting good environmental stability is crucial for practical implementation. Here, an easy approach is demonstrated to achieve low resistivity Ohmic contacts between slightly doped n-type c-Si and aluminum electrodes via simple spin-coating of metal acetylacetone (MAcac) film on a c-Si surface. Contact resistivity of 1.3 mΩ cm2 (18.2 mΩ cm2 with an a-Si:H(i) passivating layer) is realized when a thin calcium acetylacetone (CaAcac) interlayer is introduced between c-Si and Al. An n-Type c-Si solar cell with a full area rear a-Si:H(i)/CaAcac/Al electron-selective contact is demonstrated with a power conversion efficiency of 21.6%. This work not only demonstrates an approach to develop highly efficient n-type c-Si solar cells with effective electron-selective passivating contacts, but also contributes toward accomplishing a simplified fabrication process for photovoltaic devices, from vacuum to solution processing.