Solution-processed all-inorganic bismuth-triiodide thin-films for photovoltaic application

Abstract

This thesis is dedicated to my family for their love and support. I'd like to thank my parents Hussein and Amal, my siblings Tania, Samir, Yusuf, Ahmad, Tala, Waleed, Deema, and Sami, and my niece and nephew Yasmeen, and Ehab. It's your unconditional love that gives me the strength and confidence to overcome any challenge. iii

Halide Mixing and Phase Segregation in Cs2AgBiX6 (X = Cl, Br, and I) Double Perovskites from Cesium-133 Solid-State NMR and Optical Spectroscopy

“…Finally, the composition formally corresponding to Cs 2 AgBiI 6 ( Figure 2 k) is a mixture of two nonperovskite phases: Cs 3 Bi 2 I 9 ( Figure 2 l) and Cs 2 AgI 3 ( Figure 2 m). This result is consistent with previous reports which identified that the double perovskite phase of Cs 2 AgBiI 6 does not form, 77 although the synthesis of its nanocrystalline form has been reported. 78 We note that the spectrum of Cs 3 Bi 2 I 9 has two peaks that correspond to two inequivalent cesium sites in the asymmetric unit cell, consistent with a previous report.…”

Potassium Iodide-Modified Lead-Free Cs3Bi2I9 Perovskites for Enhanced High-Efficiency Solar Cells

“…As a result, grain boundaries corresponding to the device substrate can obstruct vertical-charge transport while also increasing bulk trap density via extra grain-boundary recombination centers [ 34 , 43 , 44 ]. Previous research has demonstrated that adding KI to a perovskite precursor somewhat enhances film crystallinity and grain size [ 13 , 39 , 45 ]. However, the SEM images obtained in the present study slightly refine that view in the sense that the grain sizes in the perovskite films with no KI turned out to be larger than for all perovskite films with added KI, regardless of the concentration.…”