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 .
Election/Restrictions
Applicant’s election without traverse of Invention IA, which corresponds to claim 1-10, in the reply filed on April 8, 2026 is acknowledged.
Claims 11-20 withdrawn from further consideration pursuant to 37 CFR 1.142(b) as being drawn to a nonelected invention, there being no allowable generic or linking claim. Election was made without traverse in the reply filed on April 8, 2026.
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.
Receipt is acknowledged of certified copies of papers required by 37 CFR 1.55.
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”.
Conclusion
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/NWFG/Examiner, Art Unit 1759
/MELVIN C. MAYES/Supervisory Patent Examiner, Art Unit 1759
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