Multifunctional Cross-Linked Polyurethane Polymer as Interface Layer for Efficient and Stable Perovskite Solar Cells

摘要

In the past decade, perovskite solar cells (PSCs) have made remarkableprogress in improving power conversion efficiency (PCE). In order to furtherimprove the photovoltaic performance and long-term stability of PSCs, theinterface layer is essential. A multifunctional cross-linked polyurethane(CLPU) is designed and synthesized via the spontaneous quaternization ofpolyurethane and 1, 6-diiodohexane on the surface of the perovskite layer.CLPU layer cannot only effectively induce secondary crystallization andpassivate the surface defects of perovskite, reduce the non-radiativerecombination, but also effectively block the moisture invasion. By thisstrategy, Cs_(0.05)FA_(0.95)PbI_3 PSCs with excellent reproducibility, is realized,achieving a PCE of 23.14 with an open-circuit voltage of 1.11 V, ashort-circuit current density of 25.69 mA cm~(?2), and a fill factor of 0.81. Inaddition, the unencapsulated devices show enhanced stability in 35 ± 5relative humidity (RH) near 3000 h and in 65 ± 5 RH over 700 h. This studyprovides valuable insights into the role of CLPU interface layer in PSCs, whichare essential for the design of high-performance devices.