Optical Properties and Metal‐Dependent Charge Transfer in Iodido Pentelates

Abstract

Lead‐free heavy halogenido metalates are currently under intense investigation, as they show similarly promising semiconducting properties as their famous but toxic lead relatives. A major interest in this regard is the understanding and control of optical properties with the goal of designing highly efficient photoconducting materials. Here, we present two isostructural iodido pentelates (Hpyz)3E2I9 ⋅ 2H2O (pyz=pyrazine; E=Sb, Bi). Both compounds are stable up to 100 °C. We observe an inverted order of band gap sizes, 1.91 eV and 1.98 eV for the antimony and bismuth compound, respectively, compared to similar pairs of compounds. We use DFT calculations to confirm that this surprising finding can be traced back to the presence of charge transfer excitations in both compounds.

Polymeric polyiodo-chlorotellurates(iv): new supramolecular hybrids in halometalate chemistry

“…Halide complexes of Ge (ref. 28 and 29) Sn, [30][31][32] Bi, Sb, 18,[33][34][35][36] and Te (ref. [37][38][39][40] have been extensively studied in the last few years; however, they still show a low performance with no major increase in the stability due to some issues specifically related to the elements used; for instance, Sn(II) oxidation to Sn(IV).…”

Copper and silver heterometallic iodoantimonates: structure, thermal stability, and optical properties

“…The major hindrances for their actual application are associated with poor long-term stability to heat, oxygen, and moisture alongside the health and environmental hazards of lead. 10,11 This fact enforces the search for less toxic and more stable alternatives based on other p-elements, such as Ge( ii ), 12–14 Sn( ii ), 15,16 Sb( iii ), Bi( iii ), 17–19 and Te( iv ). 20–22 However, some of these have their own challenges such as the rapid oxidation of Sn( ii ) into Sn( iv ) 23 and yielding no significant increase in stability as compared to Pb( ii ) perovskites.…”