PUBLICATIONS
Heavy pnictogens-based perovskite-inspired materials: Sustainable light-harvesters for indoor photovoltaics.
The need for self-powered electronics is progressively growing in parallel with the flourishing of the Internet of Things (IoT). Although batteries are dominating as powering devices, other small systems, such as piezoelectric, thermoelectric, and photovoltaic systems, are attracting attention. These last ones can be adapted from their classical outdoor configuration to work preferentially under indoor illumination, i.e., by harvesting the spectrum emitted by LEDs and/or fluorescent lamps. However, crystalline silicon, the classical photovoltaic material for solar panels, has a bandgap not suitable for ensuring good efficiency with such spectra. With wider bandgaps, other semiconductors can come into play for this task. Still, the materials of choice, having to be integrated within households, should also satisfy the criterion of non-toxicity and maintain low-cost production. While lead-based halide perovskites cannot represent a valuable solution for this scope, due to the strong environmental and health concerns associated with the presence of Pb, analogous compounds based on the heaviest pnictogens, i.e., bismuth and antimony, could work as sustainable light-harvesters for indoor photovoltaic devices. In this Review, we focus on reporting the most recent developments of three compounds of this class: The double perovskite Cs2AgBiBr6 is first chosen as a model system for the other two, which are emerging perovskite-inspired materials, namely, Cs3Sb2I9−xClx and bismuth oxyiodide. We show the potential of these semiconductors to play a crucial role in the future market of self-powering IoT devices, which will become a large class of devices in the electronics industry in the upcoming years.
DOI: https://doi.org/10.1063/5.0161023
Optical, transport, and defect properties of Cs2AgBiBr6.
(a) Crystal structure of BiOI. BiOI is a 2D material made of BiO layers intercalated by I ions. (b) BiOI band structure. The arrow highlights the indirect nature of the bandgap. (c) Total density of states (DOS) and individual atomic contributions to it (PDOS) of BiOI. (d)Phase diagram of the Bi–O–I system, showing the stability region of BiOI as well as phases with close equilibrium conditions. Bottom: Formation energy of intrinsic point defects in BiOI at the four extremes in the phase-stable region for BiOI.
Partial density of states (PDOSs) of (a) layered and (b) dimer modifications of Cs3Sb2I9, respectively. (c) In the panel, the corresponding band structures are shown. (d) PDOSs of Cs2PbI4 (N = 4). (e) calculated band structures of Cs2PbI4(N = 1–4).
Improved Hole Extraction and Band Alignment via Interface Modification in Hole Transport Material-Free Ag/Bi Double Perovskite Solar Cells.
The need for self-powered electronics is progressively growing in parallel with the flourishing of the Internet of Things (IoT). Although batteries are dominating as powering devices, other small systems, such as piezoelectric, thermoelectric, and photovoltaic systems, are attracting attention. These last ones can be adapted from their classical outdoor configuration to work preferentially under indoor illumination, i.e., by harvesting the spectrum emitted by LEDs and/or fluorescent lamps. However, crystalline silicon, the classical photovoltaic material for solar panels, has a bandgap not suitable for ensuring good efficiency with such spectra. With wider bandgaps, other semiconductors can come into play for this task. Still, the materials of choice, having to be integrated within households, should also satisfy the criterion of non-toxicity and maintain low-cost production. While lead-based halide perovskites cannot represent a valuable solution for this scope, due to the strong environmental and health concerns associated with the presence of Pb, analogous compounds based on the heaviest pnictogens, i.e., bismuth and antimony, could work as sustainable light-harvesters for indoor photovoltaic devices. In this Review, we focus on reporting the most recent developments of three compounds of this class: The double perovskite Cs2AgBiBr6 is first chosen as a model system for the other two, which are emerging perovskite-inspired materials, namely, Cs3Sb2I9−xClx and bismuth oxyiodide. We show the potential of these semiconductors to play a crucial role in the future market of self-powering IoT devices, which will become a large class of devices in the electronics industry in the upcoming years.
DOI:https://doi.org/10.1002/solr.202300965
Sketched band diagrams of Cs2AgBiBr6 solar cell architectures. a) Classical n-i-p architecture in which Cs2AgBiBr6 is sandwiched between ETL and HTM, e.g., TiO2 and spiro-OMeTAD, respectively. The HTM creates an energy barrier for electrons and the band alignment favours the hole drift towards the electrode. b) HTM-free Cs2AgBiBr6 solar cell. No energy barrier prevents the recombination of electrons and holes at the electrode. c) 2D/3D surface modified Cs2AgBiBr6 solar cell. The 2D perovskite functions like an HTM, elevating the VBM slightly and the CBM strongly.
Schematic representation of the process used to produce 2D/3D interfaces in Cs2AgBiBr6 thin films.
Slab model considered for DFT calculations
Physico-chemical characterization of the 2D/3D modified Cs2AgBiBr6 thin films at different BABr concentrations. a) GIXRD diffractograms of the 2D/3D modified thin films, with zoom on low angles region, and of the reference un-modified DP film. b) UV-Vis absorption spectra of the 2D/3D modified thin films, of the reference and a reference film treated with only isopropanol. c) Cross-section SEM of a Cs2AgBiBr6 solar cell (scale is 2 µm) and d) top-view SEM images of the 2D/3D modified thin films and the reference DP film. Top-view SEM scales are 200 nm each.