Self-assembled organic molecule modified electron-selective contacts for silicon heterojunction solar cells

In this work, we present cost-effective, solution-processed, self-assembled organic materials for enhanced charge carrier selectivity for crystalline silicon (c-Si) heterojunction (SHJ) solar cells. Charge transport properties of two different phosphonic acid-based self-assembled molecules, 1H,1H,2H,2H-Perfluorooctanephosphonic acid (FOPA) and [2-(9H- Carbazol-9-yl)ethyl]phosphonic acid (2PACz), are investigated. Interface barrier height modification is achieved by utilizing FOPA and 2PACz between c-Si and the metal electrode at electron-selective contacts. These molecules are applied as dopant-free electron-selective contact in SHJ solar cells. Moreover, the thermal stabilities of organic layers are investigated. A promising efficiency of 16.5%, which is stable upon annealing at 200 °C is achieved for SHJ solar cell with FOPA electron-selective contact.