EP4639637A1

EP4639637A1 - Method for blending scribing trace of solar cells and solar cells with optically blended scribing trace

Info

Publication number: EP4639637A1
Application number: EP23904930.7A
Authority: EP
Inventors: Samy BENHAMZA; Chahine GHIMOUZ; Antoine HALGAND
Original assignee: Technologies Capsolaire Inc
Current assignee: Technologies Capsolaire Inc
Priority date: 2022-12-22
Filing date: 2023-12-19
Publication date: 2025-10-29
Also published as: WO2024130399A1

Abstract

The present provides different methods for optically blending a scribing trace of a solar cell. In accordance with a first method, a fluid is injected in the scribing trace of the solar cell, in a second method a substrate of the solar cell is textured and in a third method the scribing trace is shaped to reflect light to illuminate the scribing trace. The various methods may be used separately or concurrently. The solar cell using one or multiple solutions for optically blending trace of a solar call are also described.

Description

METHOD FOR BLENDING SCRIBING TRACE OF SOLAR CELLS AND SOLAR

CELLS WITH OPTICALLY BLENDED SCRIBING TRACE

TECHNICAL FIELD

[0001] The present disclosure relates to the field of solar cells, and more particularly to methods for optically blending scribing traces of solar cells and solar cells with optically blended scribing traces.

BACKGROUND

[0002] Solar panel technologies have greatly improved over the past decade and are becoming widely adopted for energy production. Solar panels are now being added directly to various structures: buildings, vehicles, devices, etc.

[0003] The addition of solar panels to semi-opaque or translucent surfaces is however less popular, as most people are optically distracted by the scribing traces.

[0004] There is therefore a need for a method for optically blending scribing traces to reduce optical distraction. There is also a need for solar panels with optically blend scribing traces and thereby address optical distraction.

SUMMARY

[0005] According to a first aspect, the present disclosure relates to a method for optically blending a scribing trace in a solar cell. The method comprises injecting an electrically inert fluid in the scribing trace, the electrically inert fluid having at least one optical property substantially similar to an optical property of one of the following layers of the solar cell: a back contact layer of the solar cell, a front contact layer of the solar cell, a light-harvesting active layer of the of the solar cell, or a color resulting to a combination of some or all of: the back contact layer, the front contact layer and the light-harvesting active layer. [0006] In accordance with a particular aspect, the electrically inert fluid is electrically insulating.

[0007] In accordance with another particular aspect, the electrically inert fluid fills a portion of the scribing trace.

[0008] In accordance with another particular aspect, the at least one optical property is one of the following: color spectrum, light reflection index, light refraction index, and opacity.

[0009] In accordance with another particular aspect, the electrically inert fluid is one of the following: an ink, a paint, or a tinted glue.

[0010] According to another aspect, the present disclosure relates to a method for optically blending a scribing trace in a solar cell. The method comprises injecting a first electrically inert fluid in a portion of the scribing trace, the first electrically inert fluid being in a color spectrum of one of the following layers of the solar cell: a back contact layer of the solar cell, a front contact layer of the solar cell, a light-harvesting active layer of the of the solar cell. The method also comprises injecting a second electrically inert fluid in the scribing trace over the first electrically inert fluid, the second electrically inert fluid being in the color spectrum of another one of the layers of the solar cell.

[0011] In accordance with another particular aspect, the method comprises texturing a substrate of the solar cell to reflect light through the scribing trace.

[0012] In accordance with another particular aspect, the texturing comprises coating an upper surface of the substrate with an electrically inert reflective fluid.

[0013] In accordance with another particular aspect, the texturing comprises coating an upper surface of the substrate accessible through the scribing trace with an electrically inert reflective fluid.

[0014] In accordance with another particular aspect, the texturing comprises applying a reflective fluid to the upper surface of the substrate accessible through the scribing trace.

[0015] In accordance with another particular aspect, the texturing comprises applying a reflective fluid through the scribing trace, the reflective fluid forming one of the following: a convex surface and a concave surface.

[0016] According to another aspect, the present disclosure relates to a method for optically blending a scribing trace in a solar cell. The method comprises shaping the scribing trace along a depth of a light-harvesting active layer of the solar cell to refract light exiting the light-harvesting active layer to illuminate an area defined by the scribing trace.

[0017] According to yet another aspect, the present disclosure relates to a solar cell comprising a back contact layer, a front contact layer, a light-harvesting active layer between the back contact layer and the front contact layer, at least one scribing trace through the back contact layer, the front contact layer, and the lightharvesting active layer, and an optical blender for optically blending the scribing trace with at least one of the back contact layer, the front contact layer and the lightharvesting active layer.

[0018] In accordance with a particular aspect, the optical blender comprises an electrically inert fluid injected in the scribing trace, the electrically inert fluid having at least one optical property substantially similar to an optical property of one of the following layers of the solar cell: the back contact layer, the front contact layer, the light-harvesting active layer, or a color resulting from a combination of some or all of: the back contact layer, the front contact layer and the light-harvesting active layer.

[0019] In accordance with another particular aspect, the electrically inert fluid is electrically insulating.

[0020] In accordance with another particular aspect, the electrically inert fluid fills a portion of the scribing trace. [0021] In accordance with another particular aspect, the at least one optical property is one of the following: color spectrum, light reflection index, light refraction index, and opacity.

[0022] In accordance with another particular aspect, the electrically inert fluid is one of the following: an ink, a paint, and a tinted glue.

[0023] In accordance with another particular aspect, the optical blender comprises: a first electrically inert fluid in a portion of the scribing trace, the first electrically inert fluid being in a color spectrum of one of the following layers of the solar cell: the back contact layer, the front contact layer, the light-harvesting active layer; and a second electrically inert fluid in the scribing trace over the first electrically inert fluid, the second electrically inert fluid being in the color spectrum of another one of the layers of the solar cell.

[0024] In accordance with another particular aspect, the optical blender comprises a textured substrate reflecting light through the scribing trace.

[0025] In accordance with another particular aspect, the textured substrate comprises an electrically inert reflective coating.

[0026] In accordance with another particular aspect, the textured substrate comprises an electrically inert reflective fluid.

[0027] In accordance with another particular aspect, the electrically inert reflective fluid forms within the scribing one of the following: a convex surface and a concave surface.

[0028] In accordance with another particular aspect, the scribing trace is shaped to refract light exiting the light-harvesting active layer to illuminate an area defined by the scribing trace thereby providing the optical blender.

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Embodiments of the disclosure will be described by way of example only with reference to the accompanying drawings, in which: [0030] Figure 1 depicts an exemplary layouts of perovskite structures;

[0031] Figure 2 is a graph illustrating power conversion efficiencies of perovskite solar cells and compares power conversion efficiencies of emerging technologies in photovoltaic research and traditional thin-film photovoltaic cells;

[0032] Figure 3 is a graph illustrating energy loss of a photon in a process of converting light into electricity for different technologies;

[0033] Figure 4 illustrates three different configurations of perovskite solar cells, namely a convention planar configuration, an inverted planar configuration, and a mesoporous configuration, where a light-harvesting active layer is represented as a perovskite layer in all three configurations for simplicity purposes;

[0034] Figure 5 is an example of layers that make up solar cells on a large surface and isolate into several bands by means of scribing;

[0035] Figure 6 illustrates a three-step scribing process;

[0036] Figures 7A-7B illustrate two examples of a cross-section of a solar cell provided with a first approach of optical blending of scribing trace;

[0037] Figures 8A-8B illustrate two examples of a cross-section of a solar cell provided with a second approach of optical blending of scribing trace; and

[0038] Figures 9A and 9B illustrate two examples of a cross-section of a solar cell provided with a third approach of optical blending of scribing trace.

DETAILED DESCRIPTION

[0039] The foregoing and other features will become more apparent upon reading of the following non-restrictive description of illustrative embodiments thereof, given by way of example only with reference to the accompanying drawings. Like numerals represent like features on the various drawings.

[0040] Various aspects of the present disclosure generally address solar cells, and more particularly methods for optically blending a scribing trace of a solar cell and a solar cell having an optically blended scribing trace. [0041] The following terminology is used throughout the present disclosure:

[0042] Solar cell: in the context of the present invention, a solar cell refers to a combination of electrode layer, light-harvesting active layer, substrate layer and at least one scribing trace, wherein the substrate layer may be flexible or rigid, and the solar cell corresponding to any generation of photovoltaic cell.

[0043] Optical blender: electrically inert fluid in a liquid, gas or powder form alone or in combination, adapted to be deposited, injected, dried and/or treated, stabilized and/or solidified in a scribing trace.

[0044] Fluid injection: may refer to any type of process known in the solar panel industry as well as in the optical industry for applying a fluid, such as for example: spin-coating, spray-coating, doctor blade coating or slot-die coating.

[0045] Throughout the present description, reference will be made, and examples provided for perovskite solar cells. This type of solar cell is used for example purposes only, and the present invention is not limited to perovskite solar cells by rather apply to any thin film type solar cell.

[0046] Furthermore, the terms "perovskite" and "perovskite structure" are often used interchangeably in the literature. Perovskite is a type of mineral that was first discovered in the Urals mountains and named after Lev Perovski (who was the founder of the Russian Geographical Society). Perovskite now refers to any compound having the same chemical structure as the mineral perovskite.

[0047] Mineral perovskite is composed of calcium, titanium and oxygen in a CaTiO3 form. In contrast, a perovskite compound is anything that has the generic form ABX3 and the same crystallographic structure as mineral perovskite. In the field of solar cells, mineral perovskite and perovskite structure are used interchangeably or identified as perovskite.

[0048] Referring to Figure 1, there is depicted exemplary layouts of perovskite network, as shown on https://www.ossila.com/en-us/paqes/perovskites- and-perovskite-solar-cells-an-introduction. As with many crystallography structures, perovskite can be structurally represented in several ways. The simplest way to imagine perovskite is to think of a large (positively charged) type A atomic or molecular cation in the center of a cube. The corners of the cube are then occupied by B atoms (also positively charged cations) and the sides of the cube are occupied by a smaller negatively charged X atom (anion).

[0049] Many effective perovskites are based on group IV metal halides (more precisely, lead), and going beyond proved difficult. It is likely that more in- depth knowledge than currently available is needed to fully explore the range of possible Perovskite structures. Lead perovskite-based solar cells are particularly good due to several factors, including high absorption in the visible regime, long load-bearing diffusion lengths, tunable no-band, and easy manufacturing (due to high fault tolerance and low temperature processing capacity).

[0050] Reference is now made concurrently to Figures 2 and 3, which respectively illustrate power conversion efficiencies of perovskite solar cells and power conversion efficiencies of emerging technologies in photovoltaic research and traditional thin-film photovoltaic cells, and energy loss of a photon in a process of converting light into electricity for different technologies. Figure 2 is a screenshot from the following webpage: https://www.nrel.qov/py/cell-efficiency.html.

[0051] Figure 2 which relies on data from the NREL Solar Cell Efficiency Table (NREL) demonstrates power conversion efficiencies of perovskite cells over the past few years, compared to emerging technologies in photovoltaic research and traditional thin-film photovoltaic cells. The graph of Figure 2 shows a dramatic increase of power conversion efficiency for perovskites over most other technologies over a relatively short period of time. In the four years following their discovery, perovskite solar cells matched the yields of cadmium telluride (CdTe), which has been in existence for over 40 years. In addition, in June 2018, perovskites solar cells have surpassed power conversion efficiency of all other thin-film and nonconcentrating technologies - including CdTe and copper, indium and gallium selenium (CIGS). Although it can be said that more resources and better infrastructures for solar cell research have been available in recent years, the dramatic increase in power conversion efficiency for perovskite solar cells remains incredibly significant and impressive.

[0052] Figures 3 and 4 were published by Green, MA, Hishikawa, Y, Dunlop, ED, Levi, DH, Hohl-Ebinger, J, Ho-Baillie, AWY in a publication titled Solar cell efficiency tables (version 52) available through Prog Photovolt Res Appl published in 2018 (volume 26, pages 427- 436) (available through the following hyperlink https://doi.orq/10.1002/pip.3040). Figure 3 represents the energy loss of a photon in the process of converting light into electricity for various technologies including perovskite. For some solar cell technologies, namely DSSC, CZTSS and Quantum dots, the energy loss can reach 50% of the energy absorbed, while perovskite solar cells regularly exceed 70% of photon energy use and have the potential for even lower energy loss. The energy loss values for perovskite solar cells are similar to those of advanced technologies (such as GaAs), but at a much lower cost. Crystalline silicon solar cells, which are probably the closest to perovskites in terms of efficiency and cost, are already up to 1000 times cheaper than advanced GaAs and perovskite solar cells have the potential to become even cheaper.

[0053] Reference is now made to Figure 4, which illustrates three different configurations of perovskite solar cells, namely a conventional planar configuration, an inverted planar configuration, and a mesoporous configuration. In the three configures illustrated on Figure 4, a light-harvesting active layer is represented as a perovskite layer, but the present invention is not limited to this material.

[0054] Several layers are required for thin film type solar cell, and three configurations for those layers are shown on Figure 4. The first perovskite solar cells were based on solid-state dye solar cells (DSSC), and therefore used a mesoporous TiO2 scaffolding. Since then, many cells have followed this pattern or have used an AI2O3 structure in a "meso-superstructure" architecture, but the high temperature steps necessary for the manufacture and instability of UV TiO2 have led to the introduction of an architecture "planar" similar to other thin film cells. After several years of lagging behind mesoporous cells in terms of efficiency, planar perovskites are now almost as effective.

[0055] Reference is now made to a publication by Ritzer, DB, Abzieher, T, Basibuyuk, A, et al. titled “Upscaling of perovskite solar modules: The synergy of fully evaporated layer fabrication and all-laser-scribed interconnections” presented in Prog Photovolt Res Appl. 2022 volume 30( 4) pages 360- 373, available at (10.1002/pip.3489). The first figure in this publication is a graph illustrating power conversion efficiency as a function of aperture area for different types of solar cell coating technique. The publication can be found at the following webpage: https://www.ossila.com/en-us/pages/perovskites-and-perovskite-solar-cells-an- introduction. The first figure from this publication confirms that whatever the main coating technique used, the smaller aperture area results in improved power conversion efficiency.

[0056] One of the challenges in obtaining an exploitable solar cell is to control the voltage and amperage generated by the solar cell, while minimizing losses due to resistance, to increase the power generated. Reference is now made to Figure 5 which is extracted from a publication by Babak Taheri, Francesca De Rossi, Giulia Lucarelli, Luigi Angelo Castriotta, Aldo Di Carlo, Thomas M. Brown, and Francesca Brunetti, titled “Laser-Scribing Optimization for Sprayed SnO2 Based Perovskite Solar Modules on Flexible Plastic Substrates” published in ACS Applied Energy Materials 2021 4 (5), 4507-4518, available at

(https://pubs.acs.orq/doi/full/10.1021/acsaem.1c00140. The publication provides an example of a system to place layers that make up solar cells on a large surface and isolate into several bands by means of scribing. Scribing is typically performed using a laser beam to remove material on some superficial layer(s) and leave the lower layers intact thereby ensuring electrical connection between bands. Figure 5 illustrates the result of the scribing process, showing the layers (Electrode, Hole Transport Layer (HTL), Perovskite, Electron Transport Layer (ETL), Transparent Conducting Oxide (TCO), and substrate) of the solar cell, three steps (P1 , P2 and P3) resulting from the scribing process, and the circulation of a current though the layers of the solar cell. More details about the three steps P1 , P2 and P3 are provided in the following, in relation to Figure 6.

[0057] Reference is now made concurrently to Figures 4 and 6. Figure 6 is an extract from a publication authored by Ritzer, DB, Abzieher, T, Basibuyuk, A, et al titled “Upscaling of perovskite solar modules: The synergy of fully evaporated layer fabrication and all-laser-scribed interconnections” published in Prog Photovolt Res Appl. 2022; 30( 4): 360- 373 available at (doi:10.1002/pip.3489). Figure 6 illustrates an exemplary three-step scribing process. The present scribing trace optical blending is not limited to the present three-step scribing process and is applicable to any solar panel scribing process.

[0058] Step P1 separates the Transparent Conducting Oxide (TCO) layer to insert therein an electrode 105.

[0059] Step P2 separates the Hole Transport Layer (HTL), the Electron Transport Layer (ETL) and the Light-harvesting active layer (shown as perovskite layer for simplicity purposes) to insert therein an hereabove an outer electrode 105.

[0060] Step P3 physically separates the ETL, the light-harvesting active layer, the HTL and the outer electrode 105 thereby creating scribing traces.

[0061] Scribing traces are visible and not aesthetic for some applications such as automotive or Building-integrated Photovoltaics (VI PV or BIPV).

[0062] The present solar cell and method alleviate the visual drawbacks of scribing by optically blending the scribing traces with surrounding layers. The expression surrounding layers is used throughout the present application to refer to layer(s) of the solar cells adjacent to the scribing trace. The present solar cell and method are appropriate for any type of solar cells, whether rigid or flexible, flat or curved. Furthermore, the present solar cell and method is applicable to all solar cells, whether 1st, 2nd, 3rd generation of photovoltaic cells; as well as to any substrate, rigid or flexible.

[0063] Three different approaches for optically blending scribing traces with surrounding layers are described. The three approaches may be used separately or concurrently. The three approaches include: injecting an electrically inert fluid in the scribing trace; texturing a substrate of the solar cell; and shaping the scribing trace along a depth of a surrounding light-harvesting active layer. Specifics of the three approaches are described below.

Electrically inert fluid

[0064] Several criteria may be considered in determining suitability of an electrically inert fluid. The following paragraphs identify several aspects which may be considered, independently or concurrently, when selecting an electrically inert fluid to be used with any of the three approaches. The aspects listed below are provided in alphabetical order, and the order of introduction of the aspects listed should not be interpreted to reflect an order of priority or relative importance.

[0065] Compatibility: the ingredients, the curing temperature, and the solvent(s) used in the composition of the electrically inert fluid are selected to prevent degradation of the solar cell materials or the functionality of the solar cell.

[0066] Durability and mechanical strength: the electrically inert fluid demonstrates tensile and/or compressive strength to accommodate thermal expansion and contraction during module construction and/or operation, and when used on flexible solar cells.

[0067] Ease of printing: the electrically inert fluid should provide appropriate resolution and fluidity for injection or application in the scribing trace of the solar cell, furthermore, preventing nozzle clogging, and be chemically and physically stable when applied.

[0068] Electrical conductivity: The electrically inert fluid is selected to not interfere with the conductivity of any of the layers of the solar cell.

[0069] Electrical insulation: The electrically inert fluid may be electrically insulating.

[0070] Electrical resistivity: The electrical resistivity of the electrically inert fluid is selected to prevent shunting between adjacent solar cells.

[0071]

[0072] Interface characteristics: the electrically inert fluid has good wetting characteristics when used with the solar cell materials, and/or adhesive strength with the solar cell materials.

[0073] Optical property: The electrically inert fluid is selected to have at least one optical property similar to an optical property of one of the layers of the solar cell, to optically blend with that layer. For example, the at least one optical property may be one of: a color or a color spectrum, light reflection index, light refraction index, and opacity. The electrically inert fluid may have an optical property which is not identical to the optical property of one of the layers of the solar cell, but the difference therebetween is visually non-distinguishable. For example, the electrically inert fluid may be selected to have multiple optical properties similar to optical properties of the solar cell. For example, the electrically inert fluid may be of a color which is visually non-distinguishable from the color of the solar cell, with a light reflection index that is visually non-distinguishable from the light reflection index of the solar cell, and an opacity after injection in the scribing trace visually non- distinguishable from the solar cell. Alternatively, the electrically inert fluid may be of a color which is visually non-distinguishable from the color of one of: the back contact layer, the front contact layer, and the light-harvesting active layer. In another alternative, the electrically inert fluid may be of a light reflection index or light refraction index which is visually non-distinguishable from the light reflection index or light refraction index of one of: the back contact layer, the front contact layer, and the light-harvesting active layer. In another alternative, the electrically inert fluid may have an opacity which is visually non-distinguishable from the opacity of one of: the back contact layer, the front contact layer, and the light-harvesting active layer.

[0074] Physical form: The electrically inert fluid may be in any of the following physical form: an ink, a paint, or a tinted glue, in liquid, gas or powder form.

[0075] In the context of the present specification, the expression electrically inert fluid is used to refer to the fluid applied or injected, while the expression optical blender refers to the electrically inert fluid cured, treated, or processed and now forming an integral part of the solar cell.

Injection

[0076] Reference is now made to Figures 7A-7B, which illustrate a crosssection of a solar cell 100 provided with two alternatives of the first approach of optical blending of scribing trace: injection.

[0077] To optically blend a scribing trace 140 with its surrounding layers

(i.e., the ETL 120, the HTL 110, the light-harvesting active layer (e.g. perovskite) 130 and the outer electrode 105), this first approach consists in injecting in the scribing trace 140 an electrically inert fluid 150. The electrically inert fluid 150 may fill completely the scribing trace 140, or only fill a portion of the scribing trace 140.

[0078] The electrically inert fluid may be injected continuously over the scribing trace and have a thickness corresponding to one or many of the surrounding layers. Alternatively, the electrically inert fluid may be injected to cover sections of the scribing trace while leaving other sections of the scribing trace exposed. For example, the electrically inert fluid may cover sections of the scribing trace using a pattern, such as for example: dash-space-dash pattern, dash-dot-dash pattern, sinusoidal stair pattern, or any pattern which optically blends the scribing trace, while using as little electrically inert fluid as possible. [0079] The electrically inert fluid may be injected in the scribing trace when in liquid or gas form or deposited in the scribing trace when in liquid or solid form. Alternatively, the electrically inert fluid may be deposited using techniques such as for example: serigraphy, flexography, etc. The electrically inert fluid may further require drying, curing, chemical or thermal treatment and/or stabilization after injection or deposited in the scribing trace. Any method known in the art for injecting, depositing, drying, curing, chemically or thermally treating and/or stabilizing in the industry of solar panel manufacturing may be used to process the electrically inert fluid.

[0080] The electrically inert fluid is also adapted for being mechanically compliant with the solar cell, i.e., has similar flexible or rigidity characteristics after appropriate processing. The electrically inert fluid is selected to have no impact on the chemistry of any of the layers of the solar cell.

[0081] Although not shown, the present method may further include sequentially injecting a first electrically inert fluid in a portion of the scribing trace, and subsequently injecting a second electrically inert fluid in the scribing trace. The first and second electrically inert fluids may be superposed or adjacent. The optical properties of the first and second electrically inert fluid may be complimentary so as to result in optical properties which are similar to the optical properties of the solar cell and thus optically blend with the various layers of the solar cell surrounding the scribing trace.

[0082] Depending on the optical properties to be obtained, the method may further include injecting more than two electrically inert fluid, either being superposed, adjacent or a combination. For example, the method may include sequentially injecting a first electrically inert fluid in a portion of the scribing trace, and subsequently injecting a second electrically inert fluid in the scribing trace. The first and second electrically inert fluids may be superposed or adjacent. The properties of the first and second electrically inert fluid may be complimentary so as to result in the desired reflective properties and thus optically blend the scribing trace with the solar cell.

[0083] Depending on the reflective properties to be obtained, the method may further include injecting more than two electrically inert reflective fluids, either being superposed, adjacent or in combination.

By reflecting the light reaching the substrate through the scribing trace, the reflected light may be diffused through the surrounding layers to create a more uniform color.

[0084] In another alternative, the electrically inert fluid is injected in the scribing trace as well as to cover the outer electrode 105. Then, some of the electrically inert fluid may be removed from the outer electrode 105, thereby leaving the electrically inert fluid in the scribing trace.

Texturing

[0085] Reference is now made to Figures 8A-8B which illustrate two cross- sectional examples of solar cells using the second approach of optical blending: texturing. Figure 8A shows texturing at the electrode 105 level, while Figure 8B shows texturing of the substrate 160.

[0086] In the example shown on Figure 8A, the upper surface of the electrode 105 is coated with an electrically inert fluid, including into the scribing. The outer layer of the electrically inert fluid 150 is afterwards textured (e.g., form a convex surface, a concave surface, or a plurality alternating convex and concave surfaces. The outer layer of the electrically inert fluid 150 may be textured using any technique known in the solar cell industry or the optical industry. The texturing of the outer layer of the electrically inert fluid 150 alters the reflective characteristics of the electrode 105 to dissimulate the scribing trace 140.

[0087] In the approach shown on Figure 8B, the substrate 160 of the solar cell is textured to reflect light filtering through the substrate 160 and into the scribing trace 140. The light reflected by the textured substrate 160 may be reflected through the scribing trace 140, reflected into at least one layer of the solar cell, or a combination of reflection through the scribing trace 140 and reflection into at least one layer of the solar cell. Thus, in this second approach, the optical blender is created by the texture applied on the substrate 160, and the texturing alters the reflective characteristics of the substrate 160 to dissimulate (e.g. optically blend) the scribing trace 140 to the layers of the solar cell 100.

[0088] Although not shown, the approaches shown in Figures 8A and 8B could further be combined and used concurrently.

Shaping

[0089] Reference is now made to Figures 9A and 9B which illustrate a cross-section of a solar cell provided with a third approach for optically blending the scribing trace: shaping. This third approach of optical blending shapes one or several layers (105,110,120, 130) of the solar cell 100 along the scribing trace 140, to refract light exiting the light-harvesting active layer 130, thereby illuminating the scribing trace 140.

[0090] Figure 9A illustrates concurrent shaping of multiple layers of the solar cell 100 along the scribing trace 140, the present method and solar cell 100 are not limited to such an approach. More particularly, the present shaping could be performed on one or multiple layers of the solar cell 100. Depending on the type and thickness of each layer (e.g. the electrode 105, the HTL 110, the light-harvesting active layer 130 and the ETL 120, shaping only one layer may be sufficient to optically blend the scribing trace 140.

[0091] In one particular embodiment, the shaping is performed along a depth of the light-harvesting active layer 130 to refract light exiting the lightharvesting active layer 130 and illuminate an area defined by the scribing trace 140. The scribing trace 140 may be shaped by a laser. The scribing trace 140 may be shaped to define a concave cross-section as shown on Figure 9A along the lightharvesting active layer 130, the HTL 110 and the electrode 105. Figure 9A shows only a cross-section of the solar cell 100. Those skilled in the art will understand that the scribing trace 140 is not localized at one cross-section of the solar cell but extends along multiple cross-sections of the solar cell 100. The present shaping may also be performed continuously along the multiple cross-sections of the solar cell.

[0092] By optimizing a geometry of the scribing trace 140, light is diffused more uniformly throughout the scribing trace 140 and the surrounding layers (105, 110,120 and/or 130), thereby optically blending the scribing trace 140 with the surrounding layers. The geometry may be shaped to correspond to the geometry illustrated on Figure 9A, or in any appropriate shape. Figure 9B illustrates an alternative shape for the scribing trace 140.

[0093] The scribing trace 140 may be shaped continuously or by sections

(not shown). For example, the scribing trace 140 may be shaped following a pattern, such as for example: dash-space-dash pattern, dash-dot-dash pattern, sinusoidal stair pattern, or any pattern which optically blends the scribing trace through light refraction. Any technique known in the art may be used for shaping the scribing trace 140.

[0094] Although described as three separate approaches, those skilled in the art will understand that the present invention is not limited to three independent optical blending methods, and that multiple methods may be used concurrently without departing from the scope of the present invention.

Solar cell

[0095] Reference is now concurrently made to Figures 7-9A. The solar cell 100 comprises the hole transport layer 110, the electrode transport layer 120, the light-harvesting active layer 130 between the hole transport layer 110 and the electrode transport layer 120. The solar cell 100 further comprises at least one scribing trace 140 through the hole transport layer 110, the electrode transport layer 120, and the light-harvesting active layer 130. The solar cell further comprises an optical blender 150 for optically blending the scribing trace 140 with at least one of the hole transport layer 110, the electrode transport layer 120 and the light- harvesting active layer 130.

[0096] In a first aspect, more particularly shown on Figure 7A, the optical blender 150 comprises an electrically inert fluid injected in the scribing trace 140. The electrically inert fluid 150 has at least one optical property substantially similar to an optical property of one of the hole transport layer 110, the electron transport layer 120, the light-harvesting active layer 130. The at least one optical property of the optical blender 150 is one of the following: color spectrum, light reflection index, light refraction index, and opacity, or a color resulting from a combination of some or all of the hole transport layer 110, the electron transport layer 120 and the lightharvesting active layer 130.

[0097] The electrically inert fluid 150 may further be electrically insulating. Although Figure 7A shows the electrically inert fluid 150 filling completely the scribing trace 140, the present solar cell is not limited to such an implementation. For example, only a portion of the scribing trace 140 may be filled with the electrically inert fluid 150. The electrically inert fluid 150 may be one of the following: an ink, a paint, and a tinted glue.

[0098] Although not shown on Figure 7A, the optical blender comprises a first electrically inert fluid in a portion of the scribing trace 140 and a second electrically inert fluid in the scribing trace 140. The second electrically inert fluid may be superposed to the first electrically inert fluid or adjacent to the first electrically inert fluid. The first electrically inert fluid may be in a color spectrum of one of the hole transport layer 110, the electron transport layer 120, the light-harvesting active layer 130. The second electrically inert fluid may be in the color spectrum of another one of the layers of the solar cell.

[0099] Referring now more specifically to Figure 8A, the optical blender comprises a textured substrate 160 reflecting light through the scribing trace 140. For example, the textured substrate 160 may comprise an electrically inert reflective coating. Alternatively, the textured substrate 160 may comprise an electrically inert reflective fluid injected through the scribing trace 140. Although now shown, the electrically inert reflective fluid may form a convex surface and a concave surface.

[00100] Referring now more specifically to Figure 9A, the optical blender consists of shaping of at least one of the hole transport layer 110, the electron transport layer 120, the light-harvesting active layer 130 to refract light exiting the light-harvesting active layer to illuminate the scribing trace.

[00101] Although shown as three distinct approaches, the solar cell 100 could comprise one or more type of optical blender concurrently or adjacently.

[00102] In addition to optically blending the scribing trace 140 of the solar cell 100, the optical blender of any of the three approaches shown on Figures 7-9A improve the energy harvesting of the solar cell 100 by increasing the illumination of the light-harvesting active layer 130.

[00103] Although the present disclosure has been described hereinabove by way of non-restrictive, illustrative embodiments thereof, these embodiments may be modified at will within the scope of the appended claims without departing from the spirit and nature of the present disclosure.

Claims

WHAT IS CLAIMED IS:

1. A method for optically blending a scribing trace in a solar cell, the method comprising: injecting an electrically inert fluid in the scribing trace, the electrically inert fluid having at least one optical property substantially similar to an optical property of one of the following layers of the solar cell: a back contact layer of the solar cell, an front contact layer of the solar cell, a lightharvesting active layer of the of the solar cell, or a color resulting to a combination of some or all of: the back contact layer, the back contact layer and the light-harvesting active layer.

2. The method of claim 1 , wherein the electrically inert fluid is electrically insulating.

3. The method of claim 1 , wherein the electrically inert fluid fills a portion of the scribing trace.

4. The method of claim 1 , wherein the at least one optical property is one of the following: color spectrum, light reflection index, light refraction index, and opacity.

5. The method of claim 1 , wherein the electrically inert fluid is one of the following: an ink, a paint, or a tinted glue.

6. A method for optically blending a scribing trace in a solar cell, the method comprising: injecting a first electrically inert fluid in a portion of the scribing trace, the first electrically inert fluid being in a color spectrum of one of the following layers of the solar cell: a back contact layer of the solar cell, an front contact layer of the solar cell, a light-harvesting active layer of the of the solar cell; injecting a second electrically inert fluid in the scribing trace over the first electrically inert fluid, the second electrically inert fluid being in the color spectrum of another one of the layers of the solar cell.

7. A method for optically blending a scribing trace in a solar cell, the method comprising: texturing a substrate of the solar cell to reflect light through the scribing trace.

8. The method for optically blending of claim 7, wherein the texturing comprises coating an upper surface of the substrate with an electrically inert reflective fluid.

9. The method for optically blending of claim 7, wherein the texturing comprises coating an upper surface of the substrate accessible through the scribing trace with an electrically inert reflective fluid.

10. The method for optically blending of claim 7, wherein the texturing comprises applying a reflective fluid to the upper surface of the substrate accessible through the scribing trace.

11 . The method for optically blending of claim 7, wherein the texturing comprises applying a reflective fluid through the scribing trace, the reflective fluid forming one of the following: a convex surface and a concave surface.

12. A method for optically blending a scribing trace in a solar cell, the method comprising: shaping the scribing trace along a depth of a light-harvesting active layer of the solar cell to refract light exiting the light-harvesting active layer to illuminate an area defined by the scribing trace.

13. A solar cell comprising: a back contact layer; an front contact layer; a light-harvesting active layer between the back contact layer and the front contact layer; at least one scribing trace through the hole transport layer, the electrode transport layer, and the light-harvesting active layer; and an optical blender for optically blending the scribing trace with at least one of the hole transport layer, the electrode transport layer and the light-harvesting active layer.

14. The solar cell of claim 13, wherein the optical blender comprises an electrically inert fluid injected in the scribing trace, the electrically inert fluid having at least one optical property substantially similar to an optical property of one of the following layers of the solar cell: the hole transport layer, the electron transport layer, the light-harvesting active layer, or a color resulting from a combination of some or all of: the hole transport layer, the electron transport layer and the light-harvesting active layer.

15. The solar cell of claim 14, wherein the electrically inert fluid is electrically insulating.

16. The solar cell of claim 14, wherein the electrically inert fluid fills a portion of the scribing trace.

17. The solar cell of claim 14, wherein the at least one optical property is one of the following: color spectrum, light reflection index, light refraction index, and opacity.

18. The solar cell of claim 14, wherein the electrically inert fluid is one of the following: an ink, a paint, and a tinted glue.

19. The solar cell of claim 13, wherein the optical blender comprises: a first electrically inert fluid in a portion of the scribing trace, the first electrically inert fluid being in a color spectrum of one of the following layers of the solar cell: the hole transport layer, the electron transport layer, the light-harvesting active layer; a second electrically inert fluid in the scribing trace over the first electrically inert fluid, the second electrically inert fluid being in the color spectrum of another one of the layers of the solar cell.

20. The solar cell of claim 13, wherein the optical blender comprises a textured substrate reflecting light through the scribing trace.

21. The solar cell of claim 20, wherein the textured substrate comprises an electrically inert reflective coating.

22. The solar cell of claim 20, wherein the textured substrate comprises an electrically inert reflective fluid.

23. The solar cell of claim 22, wherein the electrically inert reflective fluid forms within the scribing one of the following: a convex surface and a concave surface.

24. The solar cell of claim 13, wherein the scribing trace is shaped to refract light exiting the light-harvesting active layer to illuminate an area defined by the scribing trace thereby providing the optical blender.