Tryptamine Terminated Low-Dimensional Interfaces Enabled High Performance Perovskite/Silicon Tandem Solar Cells

The construction of a high-quality interface with excellent surface passivation and carrier transport is critical to the device performance of solar cells. Low-dimensional perovskite structures are widely explored for surface passivation due to their effective suppression of interfacial defects and enhanced environmental stability. While terminal molecules for constructing low-dimensional structures provide excellent passivation, they can introduce potential barriers for charge transport if the energy levels are not well-aligned. Herein, a tryptamine molecule is explored as the terminal molecule for the construction of a low-dimensional structure for passivating the buried interface of perovskite solar cells. Based on the inclusion of nitrogen atoms in the aromatic heterocyclic structure, the terminal molecule shows an uplifted HOMO level that aligns well with the perovskite skeleton, giving rise to enhanced orbit coupling. Therefore, this low-dimensional structure enables excellent surface passivation and interfacial carrier transport simultaneously, generating an outstanding open-circuit voltage (V_OC) up to 1.266 V and an efficiency of 23.53% for single-junction wide-bandgap (1.68 eV) perovskite solar cells. This improvement enables the fabrication of the perovskite/silicon tandem solar cell with an efficiency of 33.22% (32.88% assessed by a third party) and a V_OC of 1.987 V. Moreover, the fast carrier transport at the interface suppressed the halide phase segregation, bringing much enhanced operation stability.