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Indium tin oxide (ITO) coated Willow glass is an excellent substrate for roll-to-roll manufacturing of perovskite solar cells (PSCs) but can have large variability in its optical and electrical properties. Photonic curing uses intense light pulses instead of heat to process materials and has the potential to facilitate faster processing speeds in roll-to-roll manufacturing to upscale the production of PSCs. The substrate materials’ properties play an integral role in the photonic curing outcome. Here, we present the effect of ITO transmission on the photonic curing of NiO sol-gel precursors into metal oxide and consequently the PSC performance. 

Although cyclic voltammetry (CV) measurements in solution have been widely used to determine the highest occupied molecular orbital energy (E_HOMO) of semiconducting organic molecules, an understanding of the experimentally observed discrepancies due to the solvent used is lacking. To explain these differences, we investigate the solvent effects onE_HOMOby combining density functional theory and molecular dynamics calculations for four donor molecules with a common backbone moiety. We compare the experimentalE_HOMOvalues to the calculated values obtained from either implicit or first solvation shell theories. We find that the first solvation shell method can capture theE_HOMOvariation arising from the functional groups in solution, unlike the implicit method. We further applied the first solvation shell method to other semiconducting organic molecules measured in solutions for different solvents. We find that theE_HOMOobtained using an implicit method is insensitive to solvent choice. The first solvation shell, however, producesE_HOMOvalues that are sensitive to solvent choices and agrees with published experimental results. The solvent sensitivity arises from a hierarchy of three effects: (1) the solute electronic state within a surrounding dielectric continuum, (2) ambient temperature or solvent atoms changing the solute geometry, and (3) electronic interactions between the solute and solvents. The implicit method, on the other hand, only captures the effect of a dielectric environment. Our findings suggest thatE_HOMOobtained by CV measurements should account for the influence of solvent when the results are reported, interpreted, or compared to other molecules.

 

The thermal stability and decomposition pathway of formamidinium iodide (FAI, HC(NH 2 ) 2 I) in contact with NiO and TiO 2 are investigated by combined experimental studies and density functional theory (DFT) calculations. Based on the decomposition temperature, we find that the stability decreases as FAI ∼ FAI + TiO 2 > FAI + NiO. Moreover, FAPbI 3 in contact with NiO and TiO 2 shows similar thermal stability behaviour to FAI. The bulk decomposition of FAI occurs via the formation of sym -triazine, and can also produce HCN, and NH 4 I at ∼280 °C, which further decomposes to NH 3 and HI above 300 °C. When FAI comes into contact with NiO, the interfacial reaction triggers decomposition at a much lower temperature (∼200 °C), resulting in the formation of NiI 2 as the solid product while releasing NH 3 and H 2 O into the gas phase; sym -triazine and HCN are observed near the FAI bulk decomposition temperature. In contrast, when FAI comes into contact with TiO 2 , the decomposition temperature is similar to bulk FAI; however, HCN is released at a lower temperature (∼260 °C) compared to sym -triazine. The difference in the degradation behavior of FAI with NiO and TiO 2 is elucidated using DFT calculations. Our results show that the interfacial reaction between the organic component of perovskite material and NiO occurs similarly for MA and FA, which thereby can induce device instability.