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Halide semiconductors are undergoing a period of intense interest, buoyed by the outstanding optoelectronic properties of hybrid perovskites. It is worthwhile to consider whether related materials sharing unique aspects of the perovskite chemistry, such as the incorporation of metals that provide lone pair s electrons when integrated within the halide lattice, might yield semiconductors with comparable properties. One such metal that has not been widely studied in the context of photovoltaics is monovalent indium. In this work, we investigate a method of depositing films of indium(I) iodide, coupled with optoelectronic characterization and incorporation of these films into thin-film solar cells. We find that, although indium(I) iodide exhibits a photovoltaic effect, it is likely to be compromised by difficult-to-remove defects, e.g., iodine vacancies, which are expected to introduce recombination centers deep within the band gap.

The synthesis, characterization, and photovoltaic performance of a series of N-annulated PDI materials is presented. Four novel N-annulated PDI compounds are reported, each of which can be synthesized in gram scale without the need for purification using column chromatography. N-Annulation of the PDI chromophore results in a decrease in electron affinity and lowering of the ionization potential, and renders the chromophore insoluble in organic solvents. Installation of an alkyl group improves the solubility. Single crystal X-ray analysis reveals a bowing of the aromatic backbone and compression of phenyl rings adjacent to the N atom. A brominated N-annulated PDI derivate represents a valuable synthon for creating novel multi-PDI chromophore materials. To demonstrate the utility of the new synthon for making electron transporting materials, a dimerization strategy was employed to create a dimeric PDI material. The PDI dimer has excellent solubility and film forming ability along with energetically deep HOM...

In this work, we describe details of a two-step deposition approach that enables the preparation of continuous and well-structured thin films of Cs2SnI6, which is a one-half Sn-deficient 0-D perovskite derivative (i.e., the compound can also be written as CsSn0.5I3, with a structure consisting of isolated SnI64– octahedra). The films were characterized using powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), UV–vis spectroscopy, photoluminescence (PL), photoelectron spectroscopy (UPS, IPES, XPS), and Hall effect measurements. UV–vis and PL measurements indicate that the obtained Cs2SnI6 film is a semiconductor with a band gap of 1.6 eV. This band gap was further confirmed by the UPS and IPES spectra, which were well reproduced by the calculated density of states with the HSE hybrid functional. The Cs2SnI6 films exhibited n-type conduction with a carrier density of 6(1) × 1016 cm–3 and mobility of 2.9(3) cm2/V·s. While the computationally derived band str...

Computational, thin-film deposition, and characterization approaches have been used to examine the ternary halide semiconductor Cs3Sb2I9. Cs3Sb2I9 has two known structural modifications, the 0-D dimer form (space group P63/mmc, no. 194) and the 2-D layered form (P3m1, no. 164), which can be prepared via solution and solid-state or gas-phase reactions, respectively. Our computational investigations suggest that the layered form, which is a one-third Sb-deficient derivative of the ubiquitous perovskite structure, is a potential candidate for high-band gap photovoltaic (PV) applications. In this work, we describe details of a two-step deposition approach that enables the preparation of large grain (>1 μm) and continuous thin films of the lead-free layered perovskite derivative Cs3Sb2I9. Depending on the deposition conditions, films that are c-axis oriented or randomly oriented can be obtained. The fabricated thin films show enhanced stability under ambient air, compared to methylammonium lead(II) iodide per...