Pyramid-Matrix-like buried interface construction for Boosting the photovoltaic performance of perovskite solar cells

The buried interface plays a critical role for the photovoltaic performance and stability of perovskite solar cells (PSCs). To reconstruct the surface of buried interface with a multifunctional molecule is promising for achieving efficient and stable PSCs. Herein,1,3-Di (p-tolyl) thiourea (DPT) and 1,3-Bis (4-methoxyphenyl) thiourea (BPT) were selected as modified molecules to reconstruct the interface surface. Both experimental and density functional theory (DFT) calculation results proved that the C = S of BPT prefers to coordinate with Pb2+ in perovskite and -OCH3 at the both ends prefers to form a strong coordination bond with Sn4+ in SnO2, so that BPT molecules can be successfully riveted at the interface to form a pyramid-matrix-like construction. In such case, the existed abundant C = S bonds at the pyramid tip will directed attract lead related precursor to grow the crystal grain in order, which finally results in the formation of dense and uniform perovskite films. Moreover, such directed pyramid matrix formed by BPT also build faster charge transfer channels between perovskite and SnO2 due to their higher dipole moment, which is greatly constructive for the charge transfer and collection. These advantages cannot be realized in DPT molecules. Ultimately, the BPT based PSCs achieved the highest photoelectric conversion efficiency of 24.59 % and greatly improved stability. This work provides a novel surface reconstruction strategy of buried interface via molecules with special configuration to boost the photovoltaic performance of PSCs.