DETAILED ACTION
Response to Amendment
The amendment of 6/29/2026 is considered herein.
Claims 1, 3, 4, 6, and 8 have been amended.
Claims 2, 5, 7, 9, 20-22 have been cancelled.
Claims 1, 3, 4, 6, 8, 10-19, and 23 are pending and have been considered on the merits herein.
Claim Rejections - 35 USC § 103
The text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office action.
Claim(s) 1, 3, 4, 6, 8, 10, and 23 is/are rejected under 35 U.S.C. 103 as being unpatentable over BITTKAU et al (“Optical design of spectrally selective interlayers for perovskite/silicon heterojunction tandem solar cells”, as supplied by the Applicant with the IDS of September 19, 2025), in view of KRISTAL (US PG PUB 2020/0411798) and CHIANG et al (US PG PUB 2011/0132455).
Regarding claims 1, and 23, BITTKAU et al teaches a tandem solar cell (title), wherein the tandem solar cell comprises:
a top-layer perovskite sub-cell (figure 1) and a bottom-layer crystalline-silicon sub-cell (figure 1), and an optical regulating layer (interlayer stack, IL, second paragraph of page A753, and figure 1) provided between the top-layer perovskite sub-cell and the bottom-layer crystalline-silicon sub-cell (see figure 1);
the top-layer perovskite sub-cell is provided at a light facing surface of the tandem solar cell (the side which light impinges on the solar cell is a matter of intended use however, the structure shown in figure 1 is capable of having the perovskite exposed to light first), the bottom-layer crystalline-silicon sub-cell is provided at a shadow surface of the tandem solar cell (figure 1 when light enters the perovskite), and the top-layer perovskite sub-cell and the bottom-layer crystalline- silicon sub-cell are electrically connected to each other (shown to be series connected in figure 1 and therefore connection is implicitly disclosed. Moreover, the structure of figure 1 of the figure of BITTKAU et al utilizes the same interconnection materials and electrodes from the top and bottom subcells, rendering the connection between the two sections present, even if not expressly disclosed in BITTKAU et al.); and
the optical regulating layer (interlayer) is for reflecting at least some of target light rays that pass through the top-layer perovskite sub-cell among sunlight rays back into the top-layer perovskite sub-cell, wherein the target light rays refer to light rays whose wavelengths are in a range of 600-800 nanometers among the sunlight rays (first and second full paragraphs of page A758, wherein the interlayer reflects wavelengths from 500-750nm back into the perovskite, the substantial overlap between the claimed range, and the specific values shown in figure 4b (wherein the absorption of light increases in the perovskite/top cell with the IL compared to without, which will be attributed to the interlayer, such as at 650nm and plus or minus around 650nm) of BITTKAU et al anticipates the reflection of “at least some” of the rays within the wavelength range);
the optical regulating layer (interlayer) comprises at least one low-refractive-index layer (second component of the interlayer of the final paragraph of page A754) and at least one high-refractive-index layer (“high refractive index silicon oxide alloy with lower oxygen content”, final paragraph of page A754); and
the at least one low-refractive-index layer and the at least one high-refractive-index layer are separate (last two sentences of the last paragraph of page A754 detail the relative refractive indexes as required).
the at least one low-refractive-index layer comprises a low-refractive-index material whose refractive index is less than or equal to a first preset refractive index, and the at least one high-refractive-index layer comprises a high-refractive-index material whose refractive index is greater than or equal to a second preset refractive index, (The assignation of refractive indexes as “preset” is arbitrary and does not impart structural requirements within the structural product claim. Therefore this does not patentably distinguish the claimed structure from the prior art.)
BITTKAU et al teaches interlayer to function as a Bragg reflector in the second paragraph of page A753 with low and high refractive index layers (page A754) and a high refractive index layer of 2.17, but BITTKAU et al is silent to wherein the first preset refractive index is less than or equal to the second preset refractive index; a refractive index of the at least one low-refractive-index layer is less than or equal to 1.5, and a refractive index of the at least one high-refractive-index layer is greater than or equal to 1.9; and a maximum value of a reflectivity to the target light rays of the optical regulating layer is greater than or equal to a preset reflectivity, and the preset reflectivity is 30%- 100%.
KRISTAL teaches a Bragg reflector layer which emphasizes the reflection of desired wavelengths including a range of 580-750nm or 620-750nm, utilizing a stack of high and low reflective index materials to realize the desired reflection, just as in BITTKAU et al, as in paragraphs [0017], [0018] and [0055]. Paragraph [0055] details the use of a high-refractive-index functional layer with an index of greater than 2.5 and a low-refractive-index functional layer with an index of less than 1.5. Moreover, claim 6 teaches the use of silicon oxide and titanium oxide as the functional layers of the low and high refractive index respectively, with paragraph [0075] teaching the manipulation of the refractive index via oxide concentration as well.
CHIANG et al teaches an optical layer within a solar cell which features the same structure as that of KRISTAL (a stack of low and high refractive index layers, of silicon dioxide and titanium dioxide (paragraph [0024])), and the instant claim. CHIANG et al shows the structure of modified BITTKAU et al will feature a maximum reflectance of nearly 100% in a wavelength range of greater than 500nm in figure 3A (wherein figure 3A is taught to show the reflectivity of a stack of the materials of paragraph [0024] in paragraph [0023]). Paragraph [0024] further teaches the manipulation of the layer’s thickness to achieve the desired reflectance.
It would have been obvious to one of ordinary skill in the art to utilize the high/low refractive index layers comprising titanium and silicon oxides respectively, as in KRISTAL and CHIANG et al, for the Bragg reflector of BITTKAU et al, so as to capture the desired reflectivity of wavelengths in the desired wavelength range of incoming light which will be beneficial to increase light exposure to the top cell of BITTKAU et al. The optical regulating layer of the combination details the structure as claimed (including the presence of layers with a refractive index about 2.5 and below 1.5), obviating the relationship of the reflectivity to the preset reflectivity as claimed. The assignation of reflectivity as “preset” is arbitrary and does not impart structural requirements within the structural product claim. Therefore this does not patentably distinguish the claimed structure from the prior art. For this reason, a maximum reflectivity of nearly 100%, shown in figure 3A of CHIANG et al, will obviously be greater than or equal to anything within the “preset range” fulfilling the claim. The structure of modified BITTKAU obviously renders a maximum value of a reflectivity to the target light rays of the optical regulating layer is greater than or equal to a preset reflectivity, and the preset reflectivity is 30%- 100%.
Regarding claims 3, 4 and 6, the claims as written are directed to a value or relationship of the reflectivity to “a preset reflectivity” (between 30 and 100% per claim 1 and 40-60% in claim 6). The preset reflectivity does not impact the structure of the device itself and is interpreted to read on an intended design step but does not result in a structural difference between the claimed invention and the prior art in order to patentably distinguish the claimed invention from the prior art. Since the preset reflectivity could be arbitrarily assigned (within the ranges above) and the device of modified BITTKAU et al has a reflective interlayer as discussed in the rejection of claim 1, the claims are fulfilled as the structure would render obvious the claimed reflectivity relationships. Furthermore, CHIANG et al further evidences the structure of modified BITTKAU et al will feature the claimed relationships, as shown in figure 3A.
Regarding claim 8, modified BITTKAU et al teaches the refractive index of the low-refractive-index material and the refractive index of the high-refractive-index material, a thickness of the at least one low-refractive-index layer and a thickness of the at least one high-refractive-index layer, and a quantity of the at least one low-refractive-index layers layer and a quantity of the at least one high-refractive- index layers layer are decided according to the wavelength range of 600-800 nanometers and a preset reflectivity (This limitation is directed to how to determine the appropriate refractive indexes of the optical regulating layer but the claim is directed to a product or structure and the method by which the6 refractive index does not structurally differentiate the claimed invention from the structure of the prior art. For this reason, since modified BITTKAU et al teaches a structure consistent with the refractive indexes as claimed, modified BITTKAU et al reads on the instant claimed invention. Moreover, in the interest of compact prosecution, CHIANG et al also acknowledges the impact of thickness on the reflectivity of the low and high refractive index layers in paragraph [0024], rendering it obvious to manipulate thickness as desired.).
Regarding claim 10, KRISTAL and CHIANG et al both teach the use of silicon oxide and titanium oxide materials as the low-refractive-index material and high-refractive-index material in claim 6 of KRISTAL and paragraph [0024) of CHIANG et al.
Claim(s) 11 is/are rejected under 35 U.S.C. 103 as being unpatentable over BITTKAU et al, in view of KRISTAL and CHIANG et al. and YAO et al (CN 101286531A, wherein an English machine translation is cited herein) are cited herein as evidence.
Regarding claim 11, BITTKAU et al teaches the top-layer perovskite sub-cell (top cell/perovskite stack of figure 1) comprises a perovskite light absorbing layer (perovskite), a first charge-carrier transporting layer (PCBM), a second charge-carrier transporting layer (PEDOT:PSS) and a first electrode (while not shown would necessarily need to be present so as to complete the electrical circuit loop, but is commonly shown to not be present in YAO et al figure 3 but taught to be included on the cover substrate (31) in paragraphs [0024] and [0048]), and
the bottom-layer crystalline-silicon sub-cell (bottom cell/µc-Si) comprises a crystalline-silicon light absorbing layer (µc-Si), a third charge-carrier transporting layer (nc-SiOx:H (n)), a fourth charge-carrier transporting layer (nc-SiOx:H (p)) and a second electrode (Ag/ZnO:Al);
the first charge-carrier transporting layer (PCMB) is provided at a light facing surface of the perovskite light absorbing layer (perovskite) (see figure 1), the second charge-carrier transporting layer (PEDOT:PSS) is provided at a shadow surface of the perovskite light absorbing layer (see figure 1), a charge-carrier selectivity corresponding to the first charge-carrier transporting layer and a charge-carrier selectivity corresponding to the second charge-carrier transporting layer are opposite (top paragraph of A754 teaches PCMB as an electron transport and PEDOT:PSS as a hole transport, 7indicative of opposite selectivity), and
the first electrode is provided on one side of the light facing surface of the perovskite light absorbing layer (necessary for circuit flow, also see evidence);
the third charge-carrier transporting layer (nc-SiOx:H (n)) is provided at a light facing surface of the crystalline-silicon light absorbing layer (silicon) (see figure 1), the fourth charge-carrier transporting layer (nc-SiOx:H (p)) is provided at a shadow surface of the crystalline-silicon light absorbing layer (see figure 1), a charge- carrier selectivity corresponding to the third charge-carrier transporting layer and a charge-carrier selectivity corresponding to the fourth charge-carrier transporting layer are opposite (n-type and p-type, respectively, as indicated in the name), and
the second electrode (Ag/ZnO:Al) is provided on one side of the shadow surface of the crystalline-silicon light absorbing layer (figure 1); and
the charge-carrier selectivity corresponding to the second charge-carrier transporting layer (PEDOT:PSS = hole transport, consistent with p-type materials) and the charge-carrier selectivity corresponding to the third charge- carrier transporting layer (nc-SiOx:H (n)) are opposite.
Claim(s) 12-15, 17 and 18 is/are rejected under 35 U.S.C. 103 as being unpatentable over BITTKAU et al, in view of KRISTAL, CHIANG et al and MENG et al (CN107195714A, wherein an English machine translation is included herein).
Regarding claim 12, BITTKAU et al teaches the second charge-carrier transporting layer(PEDOT:PSS) and the third charge-carrier transporting layer (nc-SiOx:H (n)) must be electrically connected to each other, and the presence of an ITO layer, but modified BITTKAU et al fails to realize expressly teach the electric connection between the top-layer perovskite sub-cell and the bottom-layer crystalline-silicon sub-cell.
MENG et al teaches a photovoltaic device comprising top, perovskite (1) and bottom, silicon (2) photovoltaic unit connected via a reflecting layer between the two sections, just as in BITTKAU et al, in paragraphs [0005] and [0029]. Moreover, MENG et al teaches electrical connection (4-1, 4-2, 4-3, etc.) in the shape of a slot or via within the optical isolation layer (or regulating layer of the instant application and interlayer of BITTKAU et al) between the top cell and bottom cells in paragraph [0030] (interpreted to include connection between the two charge-carrier transporting layers, even if the connection is indirect). This connectivity establishes a series connection of improved quality, as taught in paragraph [0005].
At the time of filing, it would have been obvious to utilize the electrically connective structure through the optical regulation layer, as shown in MENG et al, within the device of modified BITTKAU et al so as to establish electrical connection between the pair of cells.
Regarding claim 13, BITTKAU et al teaches the second charge-carrier transporting layer(PEDOT:PSS) and the third charge-carrier transporting layer (nc-SiOx:H (n)) and MENG et al teaches the connection of the bottom of the top cell and top of the bottom cell via channels 4-1, 4-2, etc. (paragraph [0015]). The connection of the cells at portions adjacent the optical regulation layers will render series connection to the charge-carrier transporting layers, inclusive of indirect connection.
Regarding claim 14, while BITTKAU et al teaches electrical connectivity is present between the two cells, modified BITTKAU et al fails to teach a through hole or slot component penetrating the optical regulating layer is provided in the optical regulating layer, the electrically conducting component is provided in the through hole or slot component of the optical regulating layer, one end of the electrically conducting component is connected to the second charge-carrier transporting layer, and the other end of the electrically conducting component is connected to the third charge-carrier transporting layer.
MENG et al teaches a photovoltaic device comprising top, perovskite (1) and bottom, silicon (2) photovoltaic unit connected via a reflecting layer between the two sections, just as in BITTKAU et al, in paragraphs [0005] and [0029]. Moreover, MENG et al teaches electrical connection (4-1, 4-2, 4-3, etc.) in the shape of a slot or via within the optical isolation layer (or regulating layer of the instant application and interlayer of BITTKAU et al) between the top cell and bottom cells in paragraph [0030] (interpreted to include connection between the two charge-carrier transporting layers, even if the connection is indirect).
At the time of filing, it would have been obvious to utilize the connection channels through the reflective layer of MENG et al, to provide the electrical implicitly necessary in modified BITTKAU et al, so as to provide the same desired and predictable result of series connection, via a known method. In this instance, the connection channels will provide the desired result of series connectivity in the device of modified BITTKAU et al, just as in MENG et al.
Regarding claim 15, MENG et al teaches the interface of the channels with the cells to occupy 0.1%-60% of the surface, rendering obvious the ratio of an area of a projection on the light facing surface of the through hole or slot component in the optical regulating layer to an area of a projection of the optical regulating layer on the light facing surface is less than 20%, based on overlapping ranges.
Regarding claim 17, MENG et al teaches the electrically conducting component comprises a plurality of materials including a transparent conductive material, a metal material and a mixed material comprising multiple types of metals, wherein the transparent electrically conductive material comprises at least one of indium tin oxide in paragraph [0015].
Regarding claim 18, BITTKAU et al teaches the second charge-carrier transporting layer(PEDOT:PSS) and the third charge-carrier transporting layer (nc-SiOx:H (n)) and MENG et al teaches the connection of the two cells via layer 3/4 which includes connectors (4-1, 4-2, etc.) therethrough, enabling connection of the transporting layers via the optical regulating layer.
Claim(s) 16 is/are rejected under 35 U.S.C. 103 as being unpatentable over BITTKAU et al, in view of KRISTAL, CHIANG et al, MENG et al and GUI et al (US PG PUB 2006/0180197).
Regarding claim 16, while modified BITTKAU et al teaches electrical connectivity between the top and bottom cells and their associated charge-carrier transporting layers via conductive component, modified BITTKAU et al fails to disclose the electrically conducting component is provided at a component side position of the tandem solar cell.
GUI et al teaches stacked photovoltaic devices, just as in modified BITTKAU et al, as shown in figure 5. GUI et al further teaches the series connection of the stacked devices via a side connection (135 and associated wiring).
At the time of filing, it would have been obvious to one of ordinary skill in the art to substitute the side connection of adjacent cells of GUI et al, for the via connections of modified BITTKAU et al, as the substitution of one known method of electrical connection for another will render the predictable result of electrical connection between the cells. Moreover, the use of electrical connectivity which does not impede light impingement of the lower cells and enables simpler fabrication without via construction, such as GUI et al, would enable a simpler and more effective cell, while still maintaining electrical connection.
Claim(s) 19 is/are rejected under 35 U.S.C. 103 as being unpatentable over BITTKAU et al, in view of KRISTAL, CHIANG et al, WANG et al (Wang, Rui, et al. “Constructive molecular configurations for surface-defect passivation of perovskite photovoltaics.” Science, vol. 366, no. 6472, 20 Dec. 2019, pp. 1509–1513, https://doi.org/10.1126/science.aay9698) and LEE et al (WO2020/130318, wherein US2022/0209039 is cited as an equivalent English translation).
Regarding claim 19, modified BITTKAU et al teaches the solar device of claim 11, but fails to teach the cell comprises a first passivation layer, a first anti-reflection layer and a second passivation layer; the first passivation layer is provided between the first charge-carrier transporting layer and the perovskite light absorbing layer, and the first anti-reflection layer is provided at one surface of the first charge-carrier transporting layer that is close to the perovskite light absorbing layer; and the second passivation layer is provided between the second charge-carrier transporting layer and the perovskite light absorbing layer.
WANG et al teaches a perovskite photovoltaic, just as in BITTKAU et al, as discussed in the abstract. WANG et al further teaches the use of small molecule layers (theophylline) fabricated on the surface of the perovskite layer to decrease inefficiencies such as surface trap-mediated nonradiative charge recombination (abstract). The use of passivation on the surface of the perovskite correlated to increased efficiency of the cell (see figure 4D).
At the time of filing, it would have been obvious to one of ordinary skill in the art to utilize a surface treatment of small molecules like theophylline on both surfaces of the perovskite of BITTKAU et al, in view of WANG et al, so as to increase efficiency of the device. These two coatings read on the first and second passivation layers of the instant claim and are positioned as claimed, between the perovskite and first and second charge-carrier transporting layers.
Modified BITTKAU et al fails to disclose the use of a first anti-reflective layer provided at one surface of the first charge-carrier transporting layer that is close to the perovskite light absorbing layer.
LEE et al teaches a tandem cell comprising perovskite and silicon cells, as in figure 1, just as in modified BITTKAU et al. LEE et al further teaches the use of an anti-reflective layer on top of the perovskite cell in paragraph [0082]. LEE et al teaches the use of the anti-reflective layer reduces surface reflectance, improving light conversion efficiency.
At the time of filing, it would have been obvious to one of ordinary skill in the art to utilize an anti-reflective layer on the external surface of the perovskite cell of modified BITTKAU et al, as in LEE et al to improve light conversion efficiency by decreased surface reflectivity. The location of the anti-reflective layer on the surface fulfills the claim as it places the first anti-reflective layer on top of the perovskite cell (which includes the first charge-carrier transporting layer) and is interpreted to read on “close to the perovskite layer”.
Response to Arguments
Applicant’s arguments with respect to claim(s) 1 and its dependents have been considered but are moot because the new ground of rejection does not rely on the combination of references applied in the prior rejection of record for any teaching or matter specifically challenged in the argument. However, in light of compact prosecution, the Examiner will respond to the arguments as applicable below to address the combination made by the Examiner herein.
Starting on page 10, the Applicant argues (in their first point) BITTKAU fails to teach the target light rays are in a range of 600-800 nm among the sunlight rays or the final limitation of amended claim 1. Specifically, BITTKAU doesn’t teach reflection of rays 750-800 nm.
It is the position of the Examiner that the claim does not require the reflectivity discussed in the 3rd limitation to pertain to all of the wavelengths within the range of 600-800nm, as it states the regulating layer is for reflecting “some of target light rays”, interpreted to be not all within that range, wherein reflection of rays up to 750nm in BITTKAU et al would read on “some of target light rays”. However, when considered in context of the current rejection above with KRISTAL and CHIANG et al, it is clear modified BITTKAU et al also teaches reflectivity of all the rays within 600-800nm based on the structure of BITTKAU et al in view of KRISTAL and CHIANG et al, as the same structure as that of the instant claim is present in the combination.
Moreover, further reflectivity arguments are rebutted by the evidentiary reference of CHIANG et al provided herein.
Starting on page 12, the Applicant argues (in their second point) that BITTKAU et al fails to address the “technical features with synergistic effects as a whole” wherein reflection, refractive index and thickness are explored.
Firstly, this isn’t claimed. Secondly, even if it were, it is a structural claim, not one directed to the exploration of features for optimization therefore acknowledgement that these features impact the final structure is outside the scope of the product claim. Finally, the Examiner disagrees that the prior art does not make the link between the thickness, refractive index and reflectivity of an optical layer and the benefit within a solar cell structure which has the opportunity for reabsorption of the desired transmitted wavelengths. For example, in paragraph [0024] of CHIANG et al, it is very clear the use of differing refractive index layers of a particular thickness (which is optimizable) allows for manipulation of the reflection of desired light ranges within a solar cell.
Conclusion
Applicants’ amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
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/KOURTNEY R S CARLSON/ Primary Examiner, Art Unit 1721 9/17/2026
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