Releasing charge transport barriers at low bias in perpendicularly aligned 2D halide perovskite

Abstract

2D halide perovskites have garnered significant interest due to the great potential in optoelectronic devices. The 2D Perovskites samples are structured as n layers of [MX6]4− octahedral sheets inducing strong quantum confinement effects. Here, we have synthesized a series of 2D (BA)₂MA_n-1Pb_nI_3n+1 and its 3D counterpart by controlling the particles alignment to the substrate. We have performed a comprehensive study involving electrical transport and photoconductivity effect as a function of the particle's organization: parallel, perpendicular, and disordered orientation to the electrodes. We have observed that for intermediary value of n, the 2D layered particles are aligned perpendicular to the electrode and parallel to the transport electrical current. A distinct and complex S-shape behavior in V-i curves is disclosed, suggesting two electrical resistance regimes. The sharp increase in resistance suggests the presence of electronic barriers for all samples, which is suppressed for columnar arrays of n = 2 and 3 under illumination. We suggest that this linear behavior in the photoconductivity effect is close related to the absence of electrical barriers at the interface of the particles due to perpendicular alignment to the electrodes. The absence of interfaces in a more columnar array facilitates ionic conductivity enhancing photoelectric effect. Our findings reveal distinct differences in charge transport for perpendicularly aligned 2D samples, opening up possibilities for important applications at low bias.