MULTIFUNCTIONAL SOLID-STATE DEVICES FOR SOLAR CONTROL, PHOTOVOLTAIC CONVERSION AND ARTIFICIAL LIGHTING

Abstract

A multifunctional solid-state photovoltachromic device (1) comprising at least one n-type layer (8) and at least one p-type layer (11) arranged to create a PN or PIN junction, said n-type layer (8) and p-type layer (11) comprising materials arranged to act as mixed conductors, thus allowing both charge transport and ion conduction.

Claims

1. A multifunctional solid-state photovoltachromic device comprising at least one n-type layer and at least one p-type layer arranged to create a PN or PIN junction, said n-type layer and p-type layer comprising materials arranged to act as mixed conductors, thus allowing both charge transport and ion conduction.

2. The multifunctional device of claim 1, further comprising a counter electrode layer placed on top of the device and an OLED device superimposed to said counter electrode layer, wherein the counter electrode layer is arranged to act as a first electrode of a plurality of electroluminescent layers deposited above it to obtain an electroluminescent functionality.

3. The multifunctional device claim 1 wherein the n-type layer and p-type layer are arranged to allow the coloring of the device itself by using a photo voltage generated within the device itself.

4. The multifunctional device of claim 1, comprising in progressive sequence: a substrate; a transparent conductive oxide layer; a solid-state electrolyte layer; a n-type layer; semitransparent photovoltaic layer; a p-type layer; a solid-state electrolyte layer, and a counter electrode.

5. The multi-functional device of claim 2, comprising: a substrate; transparent conductive oxide layer; solid-state electrolyte layer; a n-type layer; a semitransparent photovoltaic layer; a p-type layer; a solid-state electrolyte layer; a counter electrode; an electroluminescent multilayer; and a transparent counter-electrode.

6. The multifunctional device of claim 1, wherein the substrate is glass or polyethylene naphthalate, the transparent conductive oxide layer is indium tin oxide (ITO), fluorine tin oxide (FTO) or graphene, the n-type layer is selected from the group comprising PCBM.sub.60, TiO.sub.2, ZnO, WO.sub.3, WO.sub.3, MoO.sub.3, TiO.sub.2, V.sub.2O.sub.5 and VO.sub.2, the semitransparent photovoltaic layer perovskite, silicon or a polymer, the p-type layer is selected from the group comprising PANI, PANI:PSS, PEDOT, PEDOT:PSS, or mixed conducting oxides, the quasi solid and solid-state electrolyte layers are polymer electrolytes, proton conducting oxides, hybrid inorganic-organic polymer electrolytes or block copolymers with ionic liquids, and the counter electrode comprises a metal, a transparent conductive oxide or carbon based electrodes such as graphene and carbon nanotubes.

7. The multifunctional device of claim 6, wherein the polymer electrolytes of the quasi solid and solid-state electrolyte layers comprise ionomers, gel polymer electrolytes, plasticized polymer electrolyte, ionic rubber polymer electrolyte.

8. The multifunctional device of claim 6, wherein the metal of the counter electrode comprises Au, Al, Pt, Ag or LiF.

9. The multifunctional device of claim 6, wherein the transparent conductive oxide of the counter electrode comprises ITO, FTO, AZO.

Description

[0023] Further characteristics and advantages of the present invention will become apparent from the following description, provided merely by way of a non-limiting example, with reference to the enclosed drawings, in which:

[0024] FIG. 1 shows a sectional view of a multifunctional solid-state photovoltachromic device according to the present invention.

[0025] Briefly, in the multifunctional solid-state photovoltachromic device of the present invention (in the following simply referred to as device), an electrochromic function and a photovoltaic function are integrated thanks to the use of multifunctional solid layers. In this way, it is possible to activate several functions in a device obtained with a single stratigraphy and having a single layout on a single substrate.

[0026] The main focus of the invention is represented by the possibility of manufacturing, in a single stratigraphy of materials, and, therefore, on a single substrate, a multifunctional solid-state device capable of ensuring different features such as energy production by photovoltaic conversion, smart control of solar throughput and, finally, production of artificial lighting.

[0027] In the device of the present invention, materials with dual functionality are used to obtain PN junctions in which both of the materials act as mixed conductors, allowing both charge transport and ion conduction.

[0028] The present invention relates to a solid-state multifunctional device architecture on a single substrate, in particular photovoltachromic and photovoltaic, with twoor more than twoelectrodes.

[0029] The functionalities of the device, guaranteed by the single solid stratigraphy on one substrate, are electrochromic (EC) and photovoltaic (PV).

[0030] The features of the device according to the present invention can be summarized in the following points: [0031] architectures of solid-state multifunctional device on a single substrate; [0032] use of multifuncional materials in the stratigraphic fabrication process of the device. For example, materials usually used as electrochromic show charge (electrons or holes) transportation properties and can therefore be used in photovoltaic devices.

[0033] More specifically, the device of the present invention includes a photovoltaic device based on a p-n (or p-i-n) junction that comprises p-type and n-type materials, both having the peculiarity of being mixed conductors, i.e. being capable of conducting both charges and ions. For instance, the tungsten oxide WO.sub.3 is simultaneously able to conduct, in predetermined conditions, both electrons (n-type conduction) and ions, thus allowing the intercalation phenomenon in the electrochromic coloration process.

[0034] Similarly, mixed conductor p-type materials capable of conducting both holes (p-type conduction) and ions (electrolyte), such as polyethylendioxythiophene (PEDOT), polyaniline (PANI), etc., take part in both electrochromic and photovoltaic processes.

[0035] In this way, two materials in charge for the separation of the generated holes/electrons from a photovoltaic layer, preferably, a perovskite layer, have also the function of allowing the coloring of the electrochromic material, by using a photovoltage generated under illumination.

[0036] FIG. 1 shows a sectional view of a device 1 according to the present invention, which is obtained using stratigraphic processes per se known.

[0037] Starting from the bottom, the device 1 comprises a substrate 2, preferably glass or polyethylene naphthalate (PEN), a transparent conductive oxide layer 4, such as indium tin oxide (ITO) or fluorine tin oxide (FTO) or graphene, and a n-type layer 8, such as PCBM.sub.60, TiO.sub.2, ZnO, WO.sub.3, MoO.sub.3, TiO.sub.2, V.sub.2O.sub.5 and VO.sub.2.

[0038] On top of the n-type layer 8 there is a semitransparent photovoltaic layer 10, such as perovskite, silicon or a polymer, then a mixed ion and p-type conductor layer 11, for example semiconducting polymers such as PANI, PANI:PSS, PEDOT, PEDOT:PSS, or mixed conducting oxides, which acts also as anodic electrochromic, and on top of the device 1 a counter electrode 13, made for example of metal such as Au, Al, Pt, Ag or LiF, or transparent conductive oxide such as ITO, FTO, AZO, or of carbon based electrodes such as graphene and carbon nanotubes.

[0039] In an alternative embodiment of the present invention, the device 1 further comprises a quasi solid and solid state electrolyte layer 6 acting as ion storage layer, organic or inorganic, such as polymer electrolyte (ionomers, gel polymer electrolytes, plasticized polymer electrolyte, ionic rubber polymer electrolyte), proton conducting oxides (ceramic proton and hydride ion conductors), hybrid inorganic-organic polymer electrolytes (HIO-PE), or block copolymers with ionic liquids, placed between the transparent conductive oxide layer 4 and the n-type layer 8.

[0040] In a further alternative embodiment of the present invention, the device 1 further comprises a quasi solid and solid state electrolyte layer 12 similar to the layer 6 above indicated placed between the p-type layer 11 and the counter electrode 13.

[0041] In a further alternative embodiment of the present invention, which will be indicated in the following as reverse configuration, the device 1 has the following inverted structure.

[0042] Starting from the bottom, the device 1 comprises the substrate 2, the transparent conductive oxide layer 4, the solid state electrolyte layer 6, the p-type conductor layer 11, the semi-transparent photovoltaic layer 10, the n-type layer 8 and the transparent conductive layer 13 (counter electrode).

[0043] The device 1, of any of the embodiments above disclosed, is a solid-state photovoltaic and electrochromic device containing an innovative p-n junction on a single substrate 2. Both the materials of the layers 8 and 11 (n-type and p-type, respectively) have complementary electrochromic properties and the n-layer 8, the semitransparent photovoltaic layer 10 and the p-type layer 11 have mixed conducting properties, i.e. they conduct both ions and charge carriers (electrons or holes).

[0044] In the following, two possible operations of the device 1 will be disclosed.

[0045] The device 1, when exposed to light 100, produces a photovoltage, i.e. acts as a photovoltaic cell. As it is known in the art, the generated potential V.sub.oc is dependent on the level of quasi-Fermi of the materials present on the p and n junction.

[0046] In a first operating mode, in open circuit conditions (shown in the left part 1a of FIG. 1), the electrons coming from the photovoltaic layer 10 tends to fill the n-type electrochromic layer 8, attracting also the cations present in the p-type conductor layer 11 and in the electrolyte layer 12.

[0047] Coloration can be observed in the open-circuit condition, due to the generated voltage and the associated cations injection/attraction in the n-type electrochromic layer 8.

[0048] In closed circuit conditions (under illumination) the device 1 acts as photovoltaic producing electric energy. At this point, after the closure of a circuit (shown in the right part 1b of FIG. 1), the device 1, in addition to the production of electric current into the circuit, bleaches, albeit in a partial way, because of the energy levels of the materials involved in the stratigraphy of the device 1 itself.

[0049] In view of the above, it is clear that the device 1 is capable of both generating energy in a photovoltaic mode and to obtain an electrically induced change in color produced by photogenerated charge carriers.

[0050] This dual functionality of the p-type and n-type materials, which causes, under illumination condition, both the generation of electric energy (photovoltaic effect) and the coloration/bleach of the device 1 (electrochromic effect), the fact of being on the single substrate 2, the fact of bringing photovoltachromics on a solid-state device, the fact of ensuring a double functionality to the various layers and also to the device 1 itself, constitute aspects of significant innovation among multifunctional devices.

[0051] In a second operating mode of the device 1 of the present invention, the n-type layer 8 is a mixed ionic and electron conductor, leaving the electrochromic function to the p-type layer 11, i.e. the electrochromic functionality is attributed to the p-type layer 11 leaving the n-type layer 8 to serve both as ionic and electron conductor.

[0052] In this case, in open circuit conditions (shown in the left part 1 a of FIG. 1), the holes coming from the photovoltaic layer 10 tend to fill the p-type electrochromic layer 11, resulting in the oxidation of chromogenic anodic materials and transport of the cations into the n-type conductor layer 8 and the electrolyte layer 6.

[0053] Coloration can be observed already in the open-circuit condition, due to the photogenerated voltage and the associated cations injection in the n-type electrochromic layer 8.

[0054] In an alternative embodiment of the invention, both the n-type layer 8 and p-type 11 are mixed conductors having electrochromic complementary function, i.e. the electrochromic functionality is attributed to the p-type layer 11 as anodic electrochromic material and to the n-type layer 8 as cathodic electrochromic material.

[0055] In an alternative embodiment of the present invention, layers with dual function of electrodes are coupled one next to the other to obtain more devices arranged in tandem, as herein below disclosed. This creates devices with multiple features and simplified stratigraphy.

[0056] In this alternative embodiment of the present invention on top of the counter-electrode 13 there is firstly an electroluminescent multilayer and then a transparent counter-electrode.

[0057] The electroluminescent multilayer and the highly transparent counter-electrode act as an OLED device super-imposed to the photovoltachromic device.

[0058] In this last embodiment the device 1 acts therefore as photovoltachromic and OLED device, i.e. it has three functions (electrochromic, photovoltaic and OLED) with respect to the two functions (electrochromic and photovoltaic) of the embodiment disclosed with respect to FIG. 1.

[0059] In this last embodiment, the generated photovoltage (p-n junction or p-i-n junction) activates the electrochromic cell and, further, the overhead counter-electrode, processed in a thin transparent and conductive film over the p-type layer 11, acts as a first electrode of the stack of layers deposited above to obtain the electroluminescent functionality.

[0060] One advantage of the device of the present invention is that, thanks to the possibility to achieve, even with low temperature processes, solid-state multifunctional films on a single substrate, it is possible to adopt any substrate, whether flexible or fabric. This ensures high compatibility with technical depositions technologies, e.g. screen-printing, ink-jet printing, spray coating or roll-to-roll.

[0061] The device according to the present invention overcomes the main limitations encountered in the production of chromogenic devices, matching, however, the photovoltaic, electrochromic and lighting functionality to others, integrating, in a single stratigraphy, layers of materials enabling the operation of multiple functions.

[0062] Finally, the combination of multiple functionalities in a single device allows to reduce the overall fabrication costs of the device, which becomes therefore competitive with respect to the other available technologies.

[0063] With reference to the device 1 of the reverse configuration, one advantage is the use of an inorganic n-type layer 8 as buffer layer to enhance the deposition of the transparent conductive layer 13, and finally the superimposition of the OLED structure, with benefits in terms of functionality.

[0064] At the same time, this reverse configuration improves the overall performances of the chromogenic component of the device 1, due to the best interface properties between the electrolyte layer 6 and the conductive substrate 2.

[0065] Clearly, the principle of the invention remaining the same, the embodiments and the details of production can be varied considerably from what has been described and illustrated purely by way of non-limiting example, without departing from the scope of protection of the present invention as defined by the attached claims.