Interplay between cation composition and charge transport characteristics in GA_xFA_yMA_1-x-yPbI₃ halide perovskites

Author(s)

Minussi, F. B. ; Silva, R. M. ; Araujo, E. B.

• Document type: Journal article
• Source: Applied Physics Letters; v. 124, n. 15, p. 6-pg., 2024-04-08.

Abstract

Halide perovskites (HPs) are a well-known class of mixed electronic and ionic conductors with diverse applications in optoelectronic devices. The simultaneous transport of ionic and electronic carriers has beneficial and detrimental effects depending on the intended applications. There is an extensive understanding of the charge transport characteristics in HPs since the phenomenon is of applied relevance. However, considering that several applications use compositions containing mixed cations, a deeper understanding of how the degree of substitution and the characteristics of the substituent cations affect the charge transport characteristics is needed. To this end, we experimentally studied the ionic conductivity ( sigma (ion)), current-voltage hysteresis ( J- E hysteresis), mobility ( mu (e)) and density ( n e) of electronic carriers, and bandgap energies ( E- g) of up to 24 compositions of methylammonium lead iodide partially substituted with guanidinium and formamidinium. The results indicate that sigma( ion), J- E hysteresis, and mu (e )decrease with the degree of substitution, with the J - E hysteresis being smaller the larger size of the substituent cation. At the same time, sigma (ion) appears to be lower in compositions with equimolar substituents, in which the entropy of mixing is maximum. On the other hand, a slight increase in n (e) was observed with the substitution degree, showing highest values for FA(+)-rich compositions, where E (g) is the lowest. The results advance the understanding of how it is possible to customize charge transport properties through the rational design of compositions in HPs. (AU)

• FAPESP's process: 17/13769-1 - Multiferroic and ferroelectric materials for energy converters: synthesis, properties, phenomenology and applications
• Grantee: José Antonio Eiras
• Support Opportunities: Research Projects - Thematic Grants