Elastic Modulus of Polycrystalline Halide Perovskite Thin Films on Substrates

Using an innovative combination of multi beam-optical sensor (MOSS) curvature and X-ray diffraction (XRD) techniques, the Young's modulus, E, of polycrystalline MAPbI3 metal-halide perovskite (MHP) thin films attached to two different types of substrates (SiO2 and Si) is measured to be in the 6.1-6.2 GPa range. This is significantly lower than that of corresponding MAPbI3 single-crystals, which offers a new avenue of tuning E of MHP thin films via microstructural tailoring for influencing the mechanical reliability of perovskite solar cells (PSCs).Comment: 9 pages, 1 figure, supplementary information (1 figure, 1 table

Connecting Interfacial Mechanical Adhesion, Efficiency, and Operational Stability in High Performance Inverted Perovskite Solar Cells

Carbazole-based self-assembled monolayers (SAMs) at the interface between the metal-halide perovskite (MHP) and the transparent conducting oxide (TCO) serve the function of hole-transport layers in p-i-n “inverted” perovskite solar cells (PSCs). Here we show that the use of an iodine-terminated carbazole-based SAM increases the interfacial mechanical adhesion dramatically (2.6-fold) and that this is responsible for substantial improvements in the interfacial morphology, photocarrier transport, and operational stability. While the improved morphology and optoelectronic properties impart high efficiency (up to 25.39%) to the PSCs, the enhanced adhesion suppresses nucleation and propagation of pores/cracks during PSC operation, resulting in the retention of 96% of the initial efficiency after 1000 h of continuous-illumination testing at the maximum power-point. This demonstrates the strong connection between judicious interfacial adhesion toughening and simultaneous enhancement in the efficiency and operational stability of p-i-n PSCs, with broader implications for the reliability and durability of perovskite photovoltaics before they can be commercialized