The performances of organometallic halide perovskite-based solar cells severely depend on the device architecture and the interface between each layer included in the device stack. In particular, the interface between the charge transporting layer and the perovskite film is crucial, since it represents both the substrate where the perovskite polycrystalline film grows, thus directly influencing the active layer morphology, and an important site for electrical charge extraction and/or recombination. Here, we focus on engineering the interface between a perovskite-polymer nanocomposite, recently developed by our group, and different commonly employed polymeric hole transporters, namely PEDOT: PSS [poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)], PEDOT, PTAA [poly(bis 4-phenyl}{2,4,6-trimethylphenyl}amine)], Poly-TPD [Poly(N,N′-bis(4-butylphenyl)-N,N′-bis(phenyl)-benzidine] Poly-TPD, in inverted planar perovskite solar cell architecture. The results show that when Poly-TPD is used as the hole transfer material, perovskite film morphology improved, suggesting an improvement in the interface between Poly-TPD and perovskite active layer. We additionally investigate the effect of the Molecular Weight (MW) of Poly-TPD on the performance of perovskite solar cells. By increasing the MW, the photovoltaic performances of the cells are enhanced, reaching power conversion efficiency as high as 16.3%.

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In this paper, the effect of a subwavelength layer thickness with positive-refractive index material on all-optical diode action in a one-dimensional photonic crystal structure is investigated. An asymmetric multilayer stack composed of Kerr-type nonlinear and linear dielectric media and a subwavelength layer is considered. Behaviour of the linear transmission defect mode and nonlinear optical bistabilities for normal incidence of wave to 1D photonic crystal structure from left and right sides are studied. It is demonstrated that, with increasing of the subwavelength layer thickness, the linear defect mode shifts to the lower frequencies. Also, the left to right one-way transmission property of the structure is changed for right to left transmission at some subwavelength layer thicknesses. The changes of lower and higher bistability intensities thresholds and difference between left to right and right to left nonlinear transmissions versus subwavelength layer thickness are graphically illustrated. The photonic crystal all-optical diode is one of the important integrated devices, which has potential applications in the field of optical computing, optical interconnection systems and integrated photonic circuits.

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