DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Priority
Acknowledgment is made of applicant’s claim for foreign priority under 35 U.S.C. 119 (a)-(d). The certified copy has been filed in parent Application No. KR 10-2022-0148131, filed on November 8, 2022.
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
Claims 1-10 are rejected under 35 U.S.C. 103 as being unpatentable over Sudo et al (JP 2015174778 A) in view of Guo et al (US Pat No 10316250).
Regarding claim 1, Sudo discloses synthesis of ZnSnP2 cores where Zn:Sn is 0.8:1, 0.9:1 or 1:1 (examples 1-3). Sudo does not disclose a shelling process for these quantum dots. Guo teaches synthesis of shells specifically around InP core quantum dots but discloses inorganic shell coatings on quantum dots are a “universal approach to tailoring their electronic structure” (Col 1 lines 39-40), that shells can produce more robust particles by passivating surface defects (Col 1 lines 40-42), and that it is “ubiquitously accepted that the formation of core/shell structures are necessary to utilize the luminescence properties of quantum dots” (Col 2 lines 44-57). It would have been prima facie obvious to one of ordinary skill in the art, as of the effective filing date, to form a shell around a ZnSnP2 core with a predictable result of passivating surface defects. Guo teaches addition of shells that are ZnSe, ZnSexS1-x where 0<x<1, or ZnS. If these shells are added to the composition taught by Sudo, then the Zn:Sn ratio would similarly drop. However, Sudo states molar ratio of Zn:Sn is typically around 1 but more Sn can be included to have a boiling point lower than synthesis temperature such that evaporation of metal precursors is suppressed. Thus, it would have been prima facie obvious to one of ordinary skill in the art, as of the effective filing date, to maintain that same ratio of Zn:Sn throughout synthesis to suppress evaporation of metal precursors. Therefore, Sudo and Guo teach the claimed “A quantum dot comprising: a core including zinc (Zn), tin (Sn) and phosphorus (P); and a shell surrounding the core, wherein a molar ratio of a number of moles of zinc to a number of moles of tin is in a range of about 0.1 to about 2”.
Regarding claim 2, Sudo and Guo teach the quantum dot of claim 1. Sudo also teaches addition of Mg (group II element) to replace some Zn in the core in Example 3 conditions 2 and 3. Sudo discloses that beyond Mg, a germanium source (Ge, group IV), a titanium source (Ti, group IV), or a silicon source (Si, group IV) can also be included to reduce the crystal lattice or widen the band gap. Sudo also teaches that it is preferable to substitute parts of the core such as divalent cation Zn2+ with another divalent cation having a smaller ionic radius such as Mg2+. Sudo does not disclose an example of a group V element. However, Guo further discloses that quantum dot cores can be doped by a transition metal, combinations of transition metals, and/or a non-metal (Col 14, lines 36-46). These dopants include group II elements such as Hg or Cd, group IV elements such as Ti, Zr, or Hf, and group V elements such as V, Nb, N, As, or Ta. It would have been prima facie obvious to one of ordinary skill in the art, as of the effective filing date, to use additional dopants, replacing portions of Sn and P with elements of the same group having a smaller ionic radius, such as any of Si, Ti, or Ge for Sn, and N for P, to reduce the crystal lattice or widen the band gap. Therefore, Sudo and Guo satisfy the claimed “The quantum dot of claim 1, wherein the core further includes at least one of: a Group II element except zinc; a Group IV element except tin; or a Group V element except phosphorus”.
Regarding claim 3, Sudo and Guo teach the quantum dot of claim 2. Sudo teaches addition of Mg (group II element) to replace some Zn in the core in Example 3 conditions 2 and 3 whereby Mg:Zn is 0.11 or 0.25. Although Sudo does not teach cases of group IV or group V elements also added in, it would have been prima facie obvious to one of ordinary skill in the art, as of the effective filing date, to keep the molar ratios of a group II element:Zn, a group IV element:Sn, and a group V element:P consistent while maintaining the molar ratio of Zn:Sn at an allowable amount as also taught by Sudo (and explained in rejection of claim 1) to arrive at the claimed invention. Thus, Sudo and Guo satisfy the claimed “The quantum dot of claim 2, wherein a molar ratio of a number of moles of the Group II element to the number of moles of zinc, a molar ratio of a number of moles of the Group IV element to the number of moles of tin, and a ratio of a number of moles of the Group V element to a number of moles of phosphorus are each independently in a range of about 0.1 to about 1”.
Regarding claim 4, Sudo and Guo teach the quantum dot of claim 1. Furthermore, Sudo teaches a core solely composed of group II, IV, and V elements. Therefore, Sudo and Guo teach the claimed “The quantum dot of claim 1, wherein the core does not comprise a Group I element, a Group III element, or a Group VI element”.
Regarding claim 5, Sudo and Guo teach the quantum dot of claim 1. Furthermore, Guo teaches ZnSe and ZnS shells (Group II-VI compounds) in examples 1 and 3. Therefore, Sudo and Guo teach the claimed “The quantum dot of claim 1, wherein the shell comprises at least one of a Group II-VI compound, a Group III-V compound, a Group III-VI compound, a Group I-III-VI compound, a Group II-V compound, a Group II-IV-V compound, or a Group IV-V compound”.
Regarding claim 6, Sudo and Guo teach the quantum dot of claim 1. Guo teaches ZnSe and ZnS shells in examples 1 and 3. Guo also discloses that the shell can comprise the formula ZnSexSe1-x where 0<x<1 to ease lattice strain between a ZnSe and ZnS shell. Therefore, Sudo and Guo satisfy the claimed “The quantum dot of claim 1, wherein the shell comprises at least one of ZnSe, ZnS, ZnSeS, GaS, or InS”.
Regarding claim 7, Sudo and Guo teach the quantum dot of claim 1. Guo teaches first shell ZnSe and second shell ZnS in examples 1 and 3. Guo also discloses that the shell can comprise the formula ZnSexSe1-x where 0<x<1 to ease lattice strain between a ZnSe and ZnS shell. Therefore, Sudo and Guo teach the claimed “The quantum dot of claim 1, wherein the shell comprises: a first shell surrounding the core; and a second shell surrounding the first shell, and each of the first shell and the second shell each independently includes at least one of ZnSe, ZnS, or ZnSeS”.
Regarding claim 8, Sudo and Guo teach the quantum dot of claim 1. Sudo and Guo do not specify the weight absorption coefficient of their quantum dots though. Guo teaches that acid etching their quantum dot cores blue shifts the absorption spectra to a wavelength of 450nm, improves morphology (more spherical), and results in fewer surface defects which would all improve the efficiency of the quantum dot (better luminescent properties as indicated by higher quantum yield in Table 1 of Guo). The weight absorption coefficient of a quantum dot is a known measure of its efficiency, so acid etching would improve this factor through reduction in surface defects and substantially improved sphericity. It would have been prima facie obvious to one of ordinary skill in the art, as of the effective filing date, to acid etch the ZnSnP2 cores of Sudo to blue shift the absorption as necessary, improve the morphology of the cores, and reduce surface defects to improve the luminescent properties and efficiency of the quantum dot composition. Furthermore, following the teachings of Sudo and Guo would lead a person of ordinary skill in the art to arrive at the quantum dot composition as claimed. The quantum dot as claimed would inherently possess a weight absorption coefficient that is equal to or greater than 350 mL/(g*cm) and could subsequently be improved through acid etching as described for the sake of luminescent efficiency. Therefore, Sudo and Guo satisfy the claimed “The quantum dot of claim 1, wherein the quantum dot has a weight absorption coefficient equal to or greater than about 350 mL·g-1·cm-1 with respect to a wavelength of about 450 nm”.
Regarding claim 9, Sudo and Guo teach the quantum dot of claim 1. Sudo does not report the absorption or emission spectra of their quantum dot core. Guo states that their non-acid etched quantum dots absorb light at around 465 and 475nm (Figs. 2-3) with emission at 542 and 634nm (Table 1). Post acid etch treatment, the quantum dots experience blue shifted absorption to 450nm (from 465 and 475nm), while the emission wavelength is mostly unchanged (531 and 634nm from 542 and 634nm, Table 1). Additionally, in column 9 lines 27-38, Guo discloses that the ability to tailor nanocrystal size enables photoemission coverage in the entire optical spectrum. Guo teaches that acid etching can decrease the size of the quantum dots, but it is well understood in the art that the synthesis parameters such as temperature, time and shelling also heavily dictates quantum dot size. It would have been prima facie obvious to one of ordinary skill in the art, as of the effective filing date, to acid etch and tailor synthesis protocols in order to blue shift absorption and produce quantum dot compositions having a desired emission in the blue to green wavelengths of light. Thus, Sudo and Guo satisfy the claimed “The quantum dot of claim 1, wherein the quantum dot absorbs light having a central wavelength in a range of about 440 nm to about 465 nm, and the quantum dot emits light having a central wavelength in a range of about 480 nm to about 560 nm”.
Regarding claim 10, Sudo and Guo teach the quantum dot of claim 1. Sudo does not report the size of their quantum dot core. Guo does teach green-emitting quantum dots (emission of 531 or 542nm with 450 or 465nm absorption/excitation) having a core of diameter 1.8nm (radius 0.9nm) and total diameter of 6.23nm (radius 3.115nm) after shelling (col 25 lines 62-67 through col 26 lines 1-3). Additionally, in column 9 lines 27-38, Guo discloses that the ability to tailor nanocrystal size enables photoemission coverage in the entire optical spectrum. Guo teaches identical core/shell compositions having the same absorption but with different emission spectra, whereby the difference in emission is attributed to different quantum dot size (diameter/radius). It would have been prima facie obvious to one of ordinary skill in the art, as of the effective filing date, to synthesize a quantum dot core as taught by Sudo to the sizing of Guo, following shelling, to modify emission spectra to a desired wavelength and arrive at the claimed invention. Thus, Sudo and Guo teach the claimed “The quantum dot of claim 1, wherein the quantum dot has a radius in a range of about 0.5 nm to about 5 nm”.
Claim 8 is rejected under 35 U.S.C. 103 as being unpatentable over Sudo et al (JP 2015174778 A) in view of Guo et al (US Pat No 10316250) as applied to claim 1 above, and further in view of Sunderland et al (US PGPub 20200243713).
Sudo and Guo teach the quantum dot composition of claim 1 but do not report a weight absorption coefficient. Guo does report their quantum dot composition having absorption or excitation at 450nm, post acid etch treatment, and that acid etch treating improves luminescent properties by reducing surface defects and improving sphericity. Sunderland teaches an identical quantum dot composition to Guo with green wavelength emission but compares thin vs thick shell layers reporting that thinner shells result in more efficient quantum dot luminescent properties. Sunderland measures the optical density at 450nm on a per mass basis in a 1cm path length cuvette reporting values of 0.33 and 0.32 cm2/mg for the thin shelled quantum dots (Table 1). The invention as claimed requires a value of 350 mL*g-1*cm-1. Given that 1mL=1cm3, this corresponds to a value of 350cm3*g-1*cm-1 or 350cm2*g-1. Furthermore, converting g-1 to mg-1 requires dividing the value by 1,000, so the invention as claimed requires a value of 0.350cm2/mg which is just above the measured value of Sunderland. Sunderland discloses that quantum dot compositions are desired to have higher blue light absorption efficiency (paragraph [0004]) and that their disclosed embodiments have can coefficients up to 0.5cm2/mg (500mL*g-1*cm-1, see paragraph [0231]). Sunderland teaches that using thin shells improves their luminescent efficiency compared to thicker shells. As described in the rejection of claim 1, one of ordinary skill in the art would arrive to the invention as claimed by utilizing a ZnSnP2 core as taught by Sudo and shelling as taught by Gudo. Furthermore, it would have been prima facie obvious to one of ordinary skill in the art, as of the effective filing date, to utilize thinner shells and acid etch treat the cores in order to improve blue light absorption efficiency to a desired value and arrive at the invention as claimed. Thus, Sudo, Guo and Sunderland satisfy the claimed “The quantum dot of claim 1, wherein the quantum dot has a weight absorption coefficient equal to or greater than about 350 mL·g-1·cm-1 with respect to a wavelength of about 450 nm
Response to Arguments
Applicant's arguments filed July 29, 2026 have been fully considered but they are not persuasive.
Regarding claim 1:
The applicant argues the shelling in Guo is specifically directed to InP core QDs and not generically to any nanoparticle core or would not be expected to have success in particular to ZnSnP2 cores as claimed. The examiner maintains the assertion that shelling is a well known avenue for surface passivation and core protection whereby such principles can be applied generally to QD cores of all compositions. As evidenced in Li et al (US PGPub 20180273839) and in Yang et al (US PGPub 20240040816), QD cores of a variety of compositions can be shelled. Both Li and Yang disclose cores of II-IV-V structure (thus, ZnSnP2) can have core-shell structure (paragraph [0013] of Li and paragraph [0051] of Yang). Therefore, the shelling principles of Guo would be expected to have reasonable success when applied to the core disclosed by Sudo as previously argued.
The applicant further argues that Guo describes shelling compatibility components that must be considered such as the shell having wider band gap than that of the core and should have a small crystal lattice mismatch with the core. The examiner maintains that such teachings of Guo would be reasonable considerations one of ordinary skill in the art would thus consider when applying the shells of Guo to a different composition such as ZnSnP2 of Sudo. Guo teaches shells of ZnSe, ZnS, and/or ZnSeS. Band gap energies are well reported for such QD core/shell structures and are generally inherent to the composition but can also vary depending on particle size among other parameters. Oshikiri et al (cited NPL) calculate theoretically and show experimentally band gaps for ZnS and ZnSe of 3.97 eV and 3.10 eV, respectively. Yokoyama et al (NPL cited by applicant in June 9 2026 IDS) disclose a band gap of ZnSnP2 around 1.68 eV. Therefore, the band gap would not be of concern when applying the shell of Guo to the core of Sudo. Pertaining to lattice mismatch, Sudo teaches ways to modify crystal lattice of the compound or widen the band gap as well if necessary. Sudo teaches addition of germanium, titanium, palladium, or silicon sources or by substituting ions such as Mg, Ti, Ge having ion radius smaller than that of Zn can reduce the crystal lattice. Thus, when applying the teachings of Guo, one of ordinary skill would be cognizant of issues with crystal lattice mismatches or issues of lattice strain when considering a core/shell structure around cores of Sudo. Furthermore, Sudo teaches ways of ameliorating such crystal lattice strains through incorporation of other ions. Thus, although Guo provides specific examples in the context of an InP core, Guo provides enough context and general teachings when applying the principles of their shells to QDs of other core compositions to have reasonably expected success.
The applicant presents an argument regarding a molar ratio recited in claim 1: “a molar ratio of a number of moles of zinc to a number of moles of tin is in a range of about 0.1 to about 2”. The applicant argues based off teachings of Guo for molar ratios of InP, ZnSe, and ZnS are calculated based on spherical InP core of a given diameter whereby no teachings of Guo would lead one to achieve a molar ratio as claimed when applied to particles of Sudo. The original position in the Action filed May 6, 2026, does not rely on teachings of Guo for the molar ratio and rather asserts maintaining the original ratio(s) provided by Sudo in their synthesis examples. The examiner respectfully reiterates that Sudo originally teaches a synthesis of ZnSnP2 cores wherein Zn:Sn are 0.8:1, 0.9:1, or 1:1 from examples 1-3 and thus would be an obvious ratio to maintain when adding shells and a parameter to consider if the shell(s) further contain Zn that would otherwise dilute/concentrate the ratio. Therefore, the argument is not persuasive.
The applicant further argues that the molar ratio referenced in the prior rejection and modifying such a ratio via excess tin to limit evaporation as taught by Sudo would not be a rationale to consider as Sudo does not teach the molar ratio range aids to maximize optical properties of the QDs as taught in the instant specification of the application. The examiner respectfully disagrees that regardless of intention of modifying a ratio, as long as the teachings lead one to arrive to the limitation as claimed, the rationale is sufficient enough to modify the teachings and render the invention/limitation as claimed as obvious. The invention as claimed does not pertain towards modifying or maintaining a particular zinc to tin ratio such that optical properties are maximized, maintained, or improved as presented in the argument. Additionally, the claim as recited is not specific to any additional zinc present in the shell but rather broadly written such that the ratio can pertain to just the core and/or the entire composition including the shell which may or may not contain further zinc/tin. Furthermore, the examples provided in Tables 1 and 2 provide zinc:tin ratios that are specific to the core, as specified in Table 1:
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. Therefore, the zinc:tin ratio taught in Sudo, which is specific to the ZnSnP2 core, leads one of ordinary skill in the art to arrive at the limitation/range as claimed as 0.8, 0.9, and 1.0 are all within 0.1 to 2.Thus, as long as the teachings lead one to arrive to the ratio, the claim/limitation as presented is rendered obvious. Furthermore, if the claimed molar ratio range is arrived to through a different rationale, the accessory improvement cited by the applicant would inherently be present in the prepared composition. Therefore, the argument is not persuasive.
The applicant argues the rejection provided in regards to dependent claim 9 pertaining to a light absorption wavelength and light emission wavelength of the quantum dot. The rejection relied on by the examiner, as noted by the applicant, is specific to the treatments and values provided by Guo which are specific to an InP core as opposed to a ZnSnP2 core. Absorption and emission properties are largely tied to the core composition of the quantum dot, thus through arrival to the quantum dot of claim 1, the composition would inherently possess such absorption and emission properties. The combination of the core of Sudo with the shells of Guo would provide such a quantum dot. Regardless, the examiner previously relied on values provided on Guo which, although specific to an InP core, provide rationale and reference qualities that one of ordinary skill in the art would likely want to maintain if implementing in display or optical devices. For instance, light absorption is often tied to an excitation source in such devices which are often reliant on UV/blue LED light sources. Thus, the blue light absorption wavelength relied upon by Guo would be obvious to maintain when utilizing a different core and could further be modified via the acid etching procedure disclosed by Guo. Guo teaches a generic acid etching that enables blue shifting absorption of QDs, albeit in examples specific to InP, that could be reasonably pursued for other core compositions. Acid etching is a well described procedure known for post-synthesis treatments that remove surface ligands and defects to improve quantum yield and stability. Additionally, both Sudo and Guo teach that properties such as size of the QD can impact light emissive properties via quantum size effect (particularly Sudo). For instance, Sudo states that particle size of their core can be controlled and that as particle size becomes smaller, light emission is generally shorter in wavelength such as UV or near UV region. The InP cores of Guo already emit light within the green wavelengths as claimed. Thus, if one desires green light emission for their quantum dot composition, the wavelength of Guo could be pursued for such purposes or the size of the nanoparticle core can be tailored, as taught by Sudo, in order to impact light emissive properties. Therefore, the argument is not persuasive.
Conclusion
THIS ACTION IS MADE FINAL. 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.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to Noa W. F. Grooms whose telephone number is (571)272-9981. The examiner can normally be reached M-F 7:30-3:30PM EST.
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/NWFG/Examiner, Art Unit 1759
/MELVIN C. MAYES/Supervisory Patent Examiner, Art Unit 1759
