Sensate will tackle inherent limitations of conventional PV energy generation technologies by developing low dimensional PV absorbers integrated with asymmetric contacts with dipoles for a new generation of optically non-intrusive, cost-efficient, sustainable and robust solar harvester devices. For this purpose, the following challenges needs to be solved:
Availability of new 1D absorbers with excellent optical and electrical properties based on chalcogenide, halide and mixed chalcogenide-halide inorganic compounds. The unique properties of this type of materials will make possible to combine for the first time high efficiency by exploiting the exclusive electric, optic and transport charge properties, together with optical tuning and excellent stability.
To design disruptive highly selective asymmetric contacts by combining the unique properties of transition metal oxides as electron and hole transport layers, enhancing the selectivity through the use of molecules with strong dipoles, including inorganic ionic compounds (LiF, BaS, KF, CsF), and very stable organic molecules (glycine, L-histidine, sarcosine, L-tryptophan).
Sensate low-dimensional / wide-bandgap PV absorbers for solar harvesters with unique optical properties: in SENSATE, and based on the previous considerations for materials design and results obtained in my group, several chalcogenide, halides and mixed chalcogenide/halides compounds will be developed including Sb2(S,Se)3, Sb2(Sn,Ge)(S,Se)4, SbOI, BiSI, Bi4I4, etc.
Highly selective asymmetric contacts with dipoles: revolutionary p- and n-type selective contacts based on the combination of metal-oxides and dipolar molecules, and inspired in concepts originally proposed in 3rd Generation PV technologies and more recently transferred to crystalline Si technologies, will be developed, by using scalable and sustainable materials and processes. The layers will be fully adapted to the characteristics required for their integration in the new disruptive thin film solar cell architectures that are described in more detail in the next sections. Among the possible selective contacts, n-type oxides like MoO3, V2O5, Nb2O5, TiO2, or ZnO; and p-type oxides like NiO, CuO, Co3O4, will be implemented and analysed as technological solutions. To enhance the selective properties of this contacts, we will combine them for the first time with dipolar molecules, including few-layers organic dipoles (glycine, L-histidine, sarcosine, L-tryptophan, etc.), as well as nanometric inorganic dipoles (LiF, BaS, KF, CsF). This innovative approach will permit to greatly enhance charge separation in the proposed devices structure, allowing for very efficient solar cells without compromising the transparency.
High efficiency / optically tuneable solar harvester: Once innovative 1D absorbers and asymmetric selective contacts with dipoles are developed, SENSATE will introduce also innovations in the thin film solar cell devices design, inspired by recent Si and 3rd generation developments. The design based on selective contacts with dipole molecules relaxes in some extent band-alignment requisites giving more freedom for the independently design and optimization of absorbers and contacts.
Sensate proposes exploiting for the first time the full optical and electrical potential of 1D thin film wide bandgap materials, combining them with disruptive selective asymmetric contacts with dipoles, to develop a ubiquitous solar harvester with customized transparency/efficiency for advanced PV applications. This will be possible through the following Sub-Objectives and the corresponding Key Performance Indicators (KPI’s) as quantifiable targets.
1D semiconductors deposition using physical routes (sequential sputtering, evaporation, chalcogenization, iodination). Using these routes, chalcogenides, halides and mixed chalcogenide/halides compounds will be synthesised and fully characterised, such as: Sb2(S,Se)3, Sb2(Sn,Ge)(S,Se)4, (Bi,Sb)OI, (Bi,Sb)SI, (Bi,Sb)4I4, (Bi,Sb)4Br4 .
KPI TARGETS- Demonstration of 1D materials with the following parameters:
Deposition of thin film metal oxides (MxOy) using chemical (atomic layer deposition – ALD) and physical (evaporation) routes as possible layers for electron/holes highly selective asymmetric contacts. Among others MoO3, V2O5, Nb2O5, TiO2, or ZnO, NiO, CuO, Co3O4, will be studied. Optimization and full characterization of the synthesized layers in regards of their structural, morphological, optical and electrical properties. Functionalization of the selective contacts with dipolar molecules deposited by evaporation (inorganic molecules) and spin-coating (organic molecules).
KPI TARGETS- Availability of p- and n-type selective contacts with the following parameters
Integration of the layers developed in the previous Sub-Objectives into solar cell prototypes based on the simplified structure: Selective-contact/Absorber/Selective-contact, with optimized thicknesses and optical/electrical properties. Full opto-electronic characterization of the solar cell devices including conversion efficiency, quantum efficiency and durability.
SENSATE is divided into 4 complementary technical work-packages (WPs), and 1 WP for dissemination and exploitation. In WP1 (Optical and electrical modelling of new architecture devices) modelling and simulation activities of new devices architecture will be implemented. This will be highly necessary due to the innovative character of the thin film devices to be implemented, and will include optical and electrical design of the different layers to be integrated into the solar cell devices. In WP2 (Functionalized asymmetric selective contacts), metal oxide compounds will be deposited and studied for their implementation as asymmetric selective contacts in disruptive PV cell architectures, and functionalized with dipolar molecules. In WP3 (1D materials with optical/electrical tuneable properties), 1D chalcogenide, halides and mixed absorbers that can cover the bandgap range between 1.50-2.70 eV will be synthesized and fully characterized as possible candidates for semi-transparent and transparent solar cells. In WP4 (Innovative devices proof of concept: assembly and characterization), all the data obtained in WP1, and the materials developed in WP2 and WP3, will be integrated into disruptive thin film solar cells with selective asymmetric contacts, for demonstrating all the proposed efficiency and transparency targets. Finally WP5 (Dissemination and possible Exploitation) will deal with all the issues related to the dissemination and exploitation strategies of the project. Detailed description of the different WPs is given in the next section.