Recuperando o uso da aproximação de massa efetiva em perovskitas híbridas de baixa dimensionalidade por meio da aproximação de bandas não parabólicas

Abstract

Commercial use of hybrid perovskite-based solar cells is almost achieving reality. Photovoltaic conversion efficiency has quickly grown, mainly to its ease synthesis and low costs. This way, hybrid perovskite structures have been shown as promising materials to be used as optoelectronics devices. Nevertheless, they still present challenges to be overcome, mainly associated with its poor structural stability. On the other hand, the Ruddlesden-Popper perovskites present organic chains restraining the hybrid perovskite layers, achieving better structural stability regarding to traditional materials. Due to its layered structure, RPPs show two-dimensional confinement to charge carriers, and can be studied applying quantum wells physics. Hence, one can analyze such heterostructured systems through effective mass and envelope function approximations. Such an approach enables understanding of Ruddlesden–Popper Perovskites properties with solving one-dimensional single electron Schrödinger equation. However, the mentioned approximations return spurious results when applied to perovskites structures, mainly the effective mass one. To get around that issue, and keep using the approximations, one proposed that the perovskite non-parabolic dispersion relation has significant effects and should take into account. Therefore, the Schrödinger equation for non-parabolic bands was numerically solved using the differentiation matrix approach. As a result, one determined that applying the effective mass approximation was possible even to RPP, recovering optical transition properties in agreement with the experimental results. The non-parabolic bands were shown to have a fundamental role and should to take into account. Besides, one showed that exciton binding energies within the quantum well complement the non-parabolicity approximation. Since effective mass approximation allows collecting electronic properties of the complete system within the properties of a single electron subject to heterostructure potential, one believes the obtained results could considerably promote the knowledge of the physical properties of two-dimensional RPPs, and other kinds of low-dimensional perovskites devices.