2 research outputs found
Poor Photovoltaic Performance of Cs<sub>3</sub>Bi<sub>2</sub>I<sub>9</sub>: An Insight through First-Principles Calculations
Bismuth-based
halide perovskite derivatives have now attracted
huge attention for photovoltaic (PV) applications after the unparalleled
success of lead-based halide perovskites. However, the performances
of PV devices based on these compounds are poor, despite theoretical
predictions. In this Article, we have investigated the electronic
structure and defect formation energies of Cs<sub>3</sub>Bi<sub>2</sub>I<sub>9</sub> using density functional theory (DFT) calculations.
The calculated electronic bandstructure indicates an indirect bandgap
and high carrier effective masses. Our calculations reveal a large
stability region for this compound; however, deep level defects are
quite prominent. Even the varying chemical potentials from the stoichiometric
region do not eliminate the presence of deep defects, ultimately limiting
photovoltaic efficiencies
Rb as an Alternative Cation for Templating Inorganic Lead-Free Perovskites for Solution Processed Photovoltaics
Even though perovskite solar cells
have reached 22% efficiency
within a very short span, the presence of lead is a major bottleneck
to its commercial application. Tin and germanium based perovskites
failed to be viable replacements due to the instability of their +2
oxidation states. Antimony could be a possible replacement, forming
perovskites with structure A<sub>3</sub>M<sub>2</sub>X<sub>9</sub>. However, solution processing of Cs, organic ammonium based Sb perovskites
result in the formation of the dimer phase with poor charge transport
properties. Here we demonstrate that Rb can template the formation
of the desired layered phase irrespective of processing methodologies,
enabling the demonstration of efficient lead-free perovskite solar
cells