Tailoring the optoelectronic properties of monolayer BA2PbI4/MoS2 heterojunction through terminal variations and defect engineering

In light of the inherent challenge posed by the simultaneous pursuit of structural stability and favorable optoelectronic characteristics in two-dimensional organic-inorganic halide perovskites, the construction of heterojunctions emerges as a promising strategy for mitigating electronic deficiencies and enhancing overall performance. Furthermore, defect engineering stands as a commonly employed technique to fine-tune the photoelectric properties of materials. In this study, we systematically investigate the pivotal vacancy defects, namely VBA and VI, within the monolayer BA2PbI4/MoS2 heterojunction system, employing first-principles calculations. Our computational findings illuminate the conductivity of MoS2 can be modulated when it interfaces with distinct surface terminations of 2D BA2PbI4, thereby exerting influence over electron flow within MoS2. Additionally, we observe a progressive transformation of p-type doped MoS2 into a heavily doped material as the concentration of BA vacancy defects increases. To further optimize the optoelectronic properties, we strategically introduce the I vacancy (Pb-Pb dimer) defect, effectively transitioning the indirect bandgap heterojunction into a direct one. Our study underscores the profound impact of different surface terminations and defect configurations on the physical attributes of the heterojunction, offering valuable insights for the fabrication of high-performance photoelectric materials.