US3408190A - Electrophotographic plate and process employing photoconductive charge transfer complexes - Google Patents

Electrophotographic plate and process employing photoconductive charge transfer complexes Download PDF

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US3408190A
US3408190A US534417A US53441766A US3408190A US 3408190 A US3408190 A US 3408190A US 534417 A US534417 A US 534417A US 53441766 A US53441766 A US 53441766A US 3408190 A US3408190 A US 3408190A
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acid
photoconductive
plate
charge transfer
lewis
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Mammino Joseph
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Xerox Corp
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Xerox Corp
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Priority to JP42013205A priority patent/JPS523301B1/ja
Priority to GB00891/67A priority patent/GB1182172A/en
Priority to DE19671302772D priority patent/DE1302772B/de
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G5/00—Recording members for original recording by exposure, e.g. to light, to heat, to electrons; Manufacture thereof; Selection of materials therefor
    • G03G5/02—Charge-receiving layers
    • G03G5/04—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor
    • G03G5/06—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor characterised by the photoconductive material being organic
    • G03G5/07—Polymeric photoconductive materials
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S430/00—Radiation imagery chemistry: process, composition, or product thereof
    • Y10S430/001—Electric or magnetic imagery, e.g., xerography, electrography, magnetography, etc. Process, composition, or product
    • Y10S430/10—Donor-acceptor complex photoconductor

Definitions

  • This invention relates to photoconductive materials, and more particularly, to their use in electrophotography.
  • images may be formed and developed on the surface of certain photoconductive materials by electrostatic means.
  • the basic Xerographic process as taught by Carlson in US. Patent 2,297,691, involves uniformly charging a photoconductive insulating layer and then exposing the layer to a light-and-shadow image which dissipates the charge on the areas of the layer which are exposed to light.
  • the electrostatic latent image formed on the layer corresponds to the configuration of the light-and-shadow image.
  • a latent electrostatic image may be formed on the plate by charging the plate in image configuration. This image is rendered visible by depositing on the image layer a finely divided electroscopic marking material called a toner.
  • the powder developing material will normally be attracted to those portions of the layer which retain a charge, thereby forming a powder image corresponding to the latent electrostatic image.
  • This powder image may then be transferred to paper or other receiving surfaces.
  • the paper then will bear the powder image which may subsequently be made permanent by heating or other suitable fixing means.
  • photoconductive insulating materials may be used in making electrophotographic plates.
  • Suitable photoconductive insulating materials such as anthracene, sulfur, selenium or mixtures thereof, have been disclosed by Carlson in US. Patent 2,297,691. These materials generally have sensitivity in the blue or near ultra-violet range, and all but selenium have a further limitation of being only slightly light sensitive. For this reason, selenium has been the most commercially accepted material for use in electrophotographic plates. Vitreous selenium, however, while desirable in most aspects, suffers from serious limitations in that its spectral response is somewhat limited to the ultra-violet, blue and green regions of the spectrum, and the preparation of vitreous selenium plates requires costly and complex procedures, such as vacuum evaporation.
  • selenium plates require the use of a separate conductive substrate layer, preferably with an additional barrier layer deposited thereon before deposition of the selenium photoconductor. Because of these economic and commercial considerations, there have been many recent efforts towards developing photoconductive insulating materials other than selenium for use in electrophotographicplates.
  • a third type plate inherently photoconductive polymers are used; frequently in combination with sensitizing dyes or Lewis acids to form photoconductive insulating layers. Again, in these plates at least one photoconductive component is necessary in the formation of the layer. While the concept of sensitizing photoconductors is, itself, commercially useful, it does have the drawback of being limited to only those materials already having substantial photoconductivity.
  • the polymeric and binder-type organic photoconductor plates of the prior art generally have the inherent disadvantages of high cost of manufacture, brittleness, and poor adhesion to supporting substrates.
  • a number of these photoconductive insulating layers have low temperature distortion properties which make them undesirable in an automatic electrophotographic apparatus which often includes powerful lamps and thermal fusing devices which tend to heat the plate.
  • the choice of physical properties has been limited by the necessity of using only inherently photoconductive materials.
  • Inorganic pigment-binder plates are limited in usefulness because they are often opaque and are thus limited to use in systems where light transmission is not required. Inorganic pigment-binder plates have the further disadvantage of being non-reusable due to high fatigue and rough surfaces which make cleaning difficult. Still another disadvantage is that the materials used have been limited to those having inherent photoconductive insulating properties.
  • Another object of this invention is to provide an economical method for the preparation of photoconductive insulating materials wherein none of the required components is by itself substantially photoconductive.
  • Another object of this invention is to provide a photoconductive insulating material suitable for use in electrophotographic plates in both single use and reusable systems.
  • Yet another object is to provide a photoconductive insulating layer for an electrophotographic plate which is substantially resistant to abrasion and has a relatively high distortion temperature.
  • Yet a further object of this invention is to provide an electrophotographic plate having a Wide range of useful physical properties.
  • a still further object of this invention is to provide photoconductive insulating layers which may be cast into self-supporting binder free photoconductive film and structures.
  • Still another object of this invention is to provide a novel combination of initially non-photoconductive insulating materials suitable for use in the manufacture of the photoconductive insulating layer of a Xerographic plate which are easily coated on a desired substrate or combined with a conductive layer.
  • Another object is to provide a transparent self-supportingphotoconductive film.
  • adaptedforxerographic imagcurring units having the formula R r w l l; O A O L R2 I I i in R and R are each selected from the group consisting wherein:
  • ⁇ n is an integer having a value of at least two.
  • the above described complex may comprise from 1 to about 100 parts of resin for every one part of Lewis acid. About 1 to about 4 parts resin for each part Lewis acid is preferred as producing a plate with the most desirable combination of photoconductive sensitivity and reusability. Best results have been obtained when using a complex comprising 2,4,7-trinitro-9-fluorenone as the Lewis acid and the resin obtained by reacting the potassium or sodium salt of bisphenol-A with p,p'-dichloro diphenylsulfone in dimethylsulfoxide and chlorobenzene. This synthesis is described in detail in Dutch Patent 6,408,130.
  • the highly desirable photoconductive insulating material is obtained which may be either cast as a self-supporting layer or may be deposited on a suitable supporting substrate. Any other suitable method of preparing a photoconductive plate from the above photoconductive material may be used. 7
  • electron acceptor complexing may be used to render inherently non-photoconductive electron donor type insulators photoconductive. This greatly increases the range of useful materials for electrophotography.
  • a Lewis acid is any electron acceptor relative to other reagents present in the system.
  • a Lewis acid will tend to accept a pair of electrons furnished by an electron donor (or Lewis base) in the process of forming a chemical compound or, in the present invention, a charge transfer complex.
  • a Lewis acid is defined for the purposes of this invention as any electron accepting material relative to the polymer to which it is complexed.
  • a charge transfer complex may be defined as a molecular complex between substantially neutral electron donor and acceptor molecules, characterized by the fact that photoexcitation produces internal electron transfer to yield a temporary excited state in which the donor is more positive and the acceptor more negative than in the ground state.
  • the donor-type insulating resins of the present invention are rendered photoconductive by the formation of charge transfer complexes with electron acceptors, or Lewis acids, and that these complexes, once formed, constitute the photoconductive elements of the plates.
  • charge transfer complexes are loose V associations containing electron donors and acceptors
  • Donor-acceptor interaction is relatively strong in the photo-excited state, i.e., the components are at least partially ionized by photo-excitation.
  • both the intrinsic absorption bands of the donor and the charge transfer bands of the complex may be used to excite photoconductivity.
  • Photoconductive insulator for the purposes of this invention is defined with reference to the practical appli-. cation in electrophotographic imaging. It is generally considered that any insulator may be rendered photoconductive through excitation by sufiiciently intense radiation of sufficiently short wavelengths. This statement applies generally to inorganic as well as to organic ma-. terials, including the inert binder resins used in binder plates, and the electron acceptor type activators and aromatic resins used in the present invention.
  • the short wavelength radiation sensitivity is not useful in practical imaging systems because sufiiciently intense sources of wavelengths below 3200 Angstrom unitsare not available, because such radiation is damaging to the human eye and because this radiation is absorbed by glass optical systems. Accordingly, for the purposes of this application, the term photoconductive insulator includes only those materials which may be characterized as follows:
  • They may be formed into continuous films which. are capable of retaining an electrostatic charge in the absence of actinic radiation.
  • the resins used in the present invention are obtained by condensing p,p -dichlorodiphenylsulfone with a suitable salt of a dihydroxy organic compound. Best results are obtained when using salts of bisphenol-A, 2,2-(4 bishydroxy-phenyl)-propane, in the preparation of the resin and this is considered to be the preferred dihydroxy com pound.
  • Other hydroxy-containing compounds such as resorcinol, hydroquinone glycols, glycerol, and mixtures thereof may be used in mixture with or in lieu of the hydroxy alkanes if desired.
  • the di(mono-hydroxyaryl)-v alkanes are preferred; with as noted above hisphenol-A being the most preferred embodiment.
  • Typical alkanes are:
  • Any suitable Lewis acid can be complexed with the above noted polysulfone resins to form the desired photoconductive material. While the mechanism of the complex chemical interreaction involved in the present process is not completely understood, it is believed that a charge transfer complex is formed having absorption bands characteristic of neither of the two components considered individually. The mixture of the two non-photoconductive components seems to have a synergistic effect which is much greater than additive.
  • Lewis acids include: quinones, such as p-benzo-quinone, 2,6-dichlorobenzoquin0ne, chloranil, naphthoquinone-( 1,4), 2,3-dichloronaphthoquinone-( 1,4), anthraquinone, Z-methylanthraquinone, 1,4dimethylanthraquinone, l-chloroanthraquinone, anthraquinone-Z-carboxylic acid, 1,S-dichloroanthraquinone, I-chloro-4-nitroanthraquinone, phenanthrene-quinone, acenapthenequinone, pyranthrenequinone, chrysenequinone, thio-naphthene-quinone, anthraquinone-1,8-disulfonic acid and anthraquinone-2-aldehyde; tri
  • acid anhydrides such as 4-nitrophenol, and picric acid
  • acid anhydrides for example, aceticanhydride, succinic anhydride, maleic anhydride, phthalic anhydride, tetrachlorophthalic anhydride, perylene 3,4,9,10-tetracarboxylic acid and chrysene-2,3,8,9-tetracarboxylic anhydride,
  • metal halides of the metals and metalloids of the groups 1B, II through to Group VIII of the periodical system for example:
  • ferric chloride tin tetrachloride (stannic chloride), arsenic trichloride,
  • arsenic tri-iodide -b0r0n halide compounds, for example: boron trifiuoride, and
  • ketones such as acetophenone
  • Additional Lewis acids include mineral acids such as the hydrogen halides, sulphuric acid and phosphoric acid; organic carboxylic acids, such as acetic acid and the substitution products thereof,
  • alpha beta-dibromo-beta-formyl-acrylic acid (mucobromic acid)
  • organic sulphonic acids such as 4-toluene sulphonic acid
  • Example I-XIII the substance to be evaluated is coated by suitable means onto a conductive substrate and dried.
  • the coated plate is connected to ground and the layer is electrically charged in the dark by a corona discharge device (positive or negative) to saturation potential using a needlepoint scorotron powered by a high voltage power supply manufactured by High Volt Power Supply Company, Condenser Products Division, Model PS-l0-1M operating at 7 kilovolts while maintaining the grid potential at 0.9 kilovolt using a Kepco, Incorporated regulated D.C. supply (O1500 volts). Charging time is 15 seconds.
  • Such corona charging is described in detail by Carlson in U.S. Patent 2,588,699.
  • the electrostatic potential due to the charge is then measured with a transparent electrometer probe without touching the layer or atfecting the charge.
  • the signal generated in the probe by the charged layer is amplified and fed into a Moseley Autograf recorder, Model 680.-
  • the graph directly plotted by the recorder indicates the magnitude of the charge on the layer and rate of decay of the charge with time.
  • the layer is illuminated by shining light onto the layer through the transparent probe using an American Optical Spencer microscope illuminator having a GE 1493 medical type incandescent lamp operating at2800 K. color temperature.
  • the illumination level is measured with a Weston Illumination Meter, Model No. 756, and is recorded in the table.
  • the numerical difference in the rate of discharge of the charge on the layer with time in the light minus the rate of discharge of the charge on the layer in the dark is considered to be a measure of the light sensitivity of the layer.
  • An electrophotographic image is produced by charging the material by corona discharge, exposing the material by projection'to a light-and-shadow image and developing the electrostatic latent image by cascade using a commercial developer. Details of this procedure are given in Example I.
  • the above preparedsolution is flow coated onto bright finished 1145-H19 aluminum foil made by the Aluminum Company of America and oven dried at about C. for about 10 minutes.
  • the dried coating thickness is about 5 microns.
  • a 6 x 6 inch portion of the above prepared plate is negatively charged to about 450 volts by means of a corona discharge device, exposed for about 15 seconds by projection using a Simmons Omega D3 enlarger equipped with an f/4.5 lens and a tungsten light source operating at 2950 K. color temperature.
  • the illumination level at the plate is about four foot candles as measured with a Weston Illumination Meter Model No. 756.
  • the plate is then developed by cascade as described by Walkup in U.S. Patent 2,618,551.
  • the developed image is then electrostatically transferred to a receiving sheet and fused by the method described by Schatfert in U.S. Patent 2,576,047.
  • the image on the sheet is of good quality and corresponds to the projected image.
  • the plate is then cleaned of residual toner and is reused as by the above described process.
  • a coating solution is prepared as described in Example I above except that the polysulfone is Bakelite Polysulfone P2300 (Union Carbide). This polysulfone has a structure similar to that given in Example I, but has a higher 'molecular weight.
  • the above prepared solution is coated
  • a coating solution is prepared as described in Example I above except that the polysulfone is Bakelite Polysulfone P3500 (Union Carbide). This resin has a structure similar to that shown in Example I, but has a still higher molecular weight.
  • the solution thus prepared is applied onto a conductive substrate as previously described and dried. A positive image corresponding to the original is produced,
  • EXAMPLE N data are tabulated. See Table I. This illustrates that increased visible light sensitivity
  • a coating Solution is P p as deSCflbed 111
  • Example may be obtained by the addition of sensitizing dyes to the 1, except that about 3 parts 9-(dicyanomethylene)-2,4,7- composition, trinitrofluorene is used in place of the 2,4,7-trinitro-9- EXAMPLE X fiuorenone.
  • the solution thus prepared is applied onto a conductive substrate as previously described and dried.
  • a ⁇ Xbout one gram of Luclte 2042 ethyl methacrylate portion of the plate is exposed and developed as in Ex- Tesln manufactllfed PY Du POIlt d6 Nem011f ample I, producing a positive image of good quality Company, Inc., is dissolved 1n a solvent blend consisting other portion of the plate is then electrometered and the of about 10 Parts methyl ethyl ketone, about P data tabulatedin'rable benzene, about 1 part acetone and about 2 parts diethyl ketone. The mixture is agitated by a stirrer until the resin EXAMPLE V is fully dissolved in the solvent blend.
  • a plate is coated, dried, charged, exposed and developed The above solution is applied onto an aluminum plate as in Example IV, except that here the Lewis acid used by suitable means and dried. is 2,3-dichloro-1,4-naphthoquinone.
  • the image produced The above plate is electrometered and the results are on this plate is of excellent quality.
  • EXAMPLE VI About 0.25 part of 2,4,7-trinitrotluorenone is added to 1 a coating solution prepared as described in Example X A coatmg SQIHUOD 1s PTeParQd aigescnbad P Exam? e above. The solution is applied onto a conductive subabov? but wlthout any fi e The resm solunon strate as described and dried. The plate is electrometered is applied onto a conductive substrate and dried. The and the data are tabulated See Table L above prepared plate is electrometered and the results tabulated. See Table I. The polysulfone resin coating with- EXAMPLE XII out Lewis acid is thus found to be non-photoconductive.
  • sensitivity represents the initial dis charge rate upon illumination in volts/100 foot candle seconds corrected for the rate of dark discharge.
  • Examples I-IV a mixture of a polysulfone resin and a Lewis acid is photoconductive.
  • Examples V-VH show that a polysulfone resin used alone, with no Lewis acid, is not photoconductive.
  • Example VIII indicates that a polysulfone resin-Lewis acid complex can be dye sensitized.
  • Examples X-XII show that the Lewis acids and sensitizing dyes used in Examples I-IV and VIII are not photoconductive in an inert Lucite binder.
  • the photoconductive composition of this invention may have other materials or colorants mixed therewith to enhance, sensitize, synergize or otherwise modify the photoconductive properties of the composition.
  • the photoconductive compositions of this invention, where suitable,' may be used in other imaging processes, such as those disclosed in copending applications Ser. Nos. 384,737, now US. Patent 3,384,565; 384,- 680; and 384,681; both now abandoned, Where their electrically photosensitive properties are beneficial.
  • a photoconductive charge transfer complex material comprising a mixture of a Lewis acid and a polysulfone resin having repeating units of the following general formula:
  • X and Y are each selected from the group consisting of hydrogen and alkyl radicals, and wherein the total number of carbon atoms in X and Y is up to 12;
  • n is an integer having a value of at least 2, said photoconductive charge transfer complex having at least onenew absorption band within a range of from about 3200 to about 7500 Angstrom units.
  • the photoconductive charge transfer complex material of claim 1 comprising from about 1 to about 100 parts of said resin for every one part of said Lewis acid.
  • the photoconductive charge transfer complex material of claim 1 wherein said resin comprises the reaction product of p,p-dichlorodiphenylsulfone and 2,2-bis-(4- hydroxy-phenyl) propane.
  • the photoconductive charge transfer complex material of claim 3 comprising from about 1 to about 100 parts of said resin for every one part of said Lewis acid.
  • the photoconductive charge transfer complex material of claim 1 wherein said Lewis acid is selected from the group consisting of 2,4,7-trinitro-9-fiuorenone, 9-(dicyanomethylene -2,4,7-trinitro-fluorene, 2,3-dichloro-1,4- naphthaquinone, and mixtures thereof.
  • a process for the preparation of a photoconductive charge transfer complex material which comprises mixing a Lewis acid and a polysulfone resin having repeating units of the following formula:
  • X and Y are each selected from the group consisting of hydrogen and alkyl radicals, and wherein the total number of carbon atoms in X and Y is up to 12;
  • n is an integer having a value of at least 2, said charge transfer complex having at least one new absorption band within a range of from about 3200 to about 7500 Angstrom units.
  • said resin comprises the reaction product of p,p'-dichlorodiphenylsulfone and 2,2-bis-(4-l1ydroxy-phenyl) propane.
  • Lewis acid is selected from the group consisting of 2,4,7-trinitro-9-fluorenone, 9-(dicyanomethylene)-2,4,7-trinitro-fluorene, 2,3
  • Lewis acid comprises 2,4,7-trinitro-9-fluorenone.
  • An electrophotographic plate comprising a support substrate having fixed to the surface thereof a photoconductive charge transfer complex material comprising a mixture of a Lewis acid and a polysulfone resin comprising recurring units having the formula:
  • X and Y are each selected from the group consisting of hydrogen and alkyl radicals, and wherein the total number of carbon atoms in X and Y is up to 12;
  • n is an integer having a value of at least 2, said photoconductive charge transfer complex having at least one new absorption band within the range of from about 3200 to about 7500 Angstrom units.
  • Lewis acid is selected from the group consisting of 2,4,7-trinitro-9-fluorenone, 9-(dicyanomethylene)-2,4,7- trinitro-fluorene, 2,3-dichloro-1,4-naphthaquinone, and mixtures thereof.
  • the electrophotographic plate of claim 12 comprising from about 1 to about 100 parts of said resin for every one part of said Lewis acid.
  • a method of forming a latent electrostatic charge pattern comprising charging the electrophotographic plate of claim 12 and exposing said plate to a pattern of activating electromagnetic radiation.
  • a method of forming a latent electrostatic pattern wherein the plate of claim 12 is electrostatically charged in an image pattern.
  • the process of claim 19 further including the steps of transferring said marking particles to the surface of a receiving sheet, and recharging, exposing and developing 5 said plate to produce at least more than one copy of the original.

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US534417A 1966-03-15 1966-03-15 Electrophotographic plate and process employing photoconductive charge transfer complexes Expired - Lifetime US3408190A (en)

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US534417A US3408190A (en) 1966-03-15 1966-03-15 Electrophotographic plate and process employing photoconductive charge transfer complexes
JP42013205A JPS523301B1 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1966-03-15 1967-03-03
GB00891/67A GB1182172A (en) 1966-03-15 1967-03-08 Electrophotographic Plate and process
DE19671302772D DE1302772B (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1966-03-15 1967-03-15

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Cited By (10)

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US3864126A (en) * 1973-01-10 1975-02-04 Canon Kk Organic photoconductor with carboxy group containing fluorene or fluorore
US4066454A (en) * 1973-11-19 1978-01-03 Kabushiki Kaisha Ricoh Electrophotographic light-sensitive material containing indenothiophenone or its derivative and process of preparing indenothiophenone and its derivative
US4069046A (en) * 1971-02-19 1978-01-17 Xerox Corporation Polymerized vinyl carbazoles sensitized by nitro-substituted 9-dicyanomethylene fluorenes
USRE29554E (en) * 1969-06-05 1978-02-28 Addressograph-Multigraph Corporation Organic photoconductive members comprising dicyanomethylene substituted fluorene sensitizers
US4078927A (en) * 1973-12-13 1978-03-14 Xerox Corporation Photoconductive printing master
US4609602A (en) * 1985-03-08 1986-09-02 Xerox Corporation Photoresponsive imaging members with electron transporting layers
EP0290270A3 (en) * 1987-05-07 1990-05-09 Matsushita Electric Industrial Co., Ltd. Electrophotography photosensitive member and a method for fabricating same
US9125829B2 (en) 2012-08-17 2015-09-08 Hallstar Innovations Corp. Method of photostabilizing UV absorbers, particularly dibenzyolmethane derivatives, e.g., Avobenzone, with cyano-containing fused tricyclic compounds
US9145383B2 (en) 2012-08-10 2015-09-29 Hallstar Innovations Corp. Compositions, apparatus, systems, and methods for resolving electronic excited states
US9867800B2 (en) 2012-08-10 2018-01-16 Hallstar Innovations Corp. Method of quenching singlet and triplet excited states of pigments, such as porphyrin compounds, particularly protoporphyrin IX, with conjugated fused tricyclic compounds have electron withdrawing groups, to reduce generation of reactive oxygen species, particularly singlet oxygen

Citations (2)

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US3287122A (en) * 1961-07-24 1966-11-22 Azoplate Corp Process for the sensitization of photoconductors
US3287121A (en) * 1961-07-24 1966-11-22 Azoplate Corp Process for the sensitization of photoconductors

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3287122A (en) * 1961-07-24 1966-11-22 Azoplate Corp Process for the sensitization of photoconductors
US3287121A (en) * 1961-07-24 1966-11-22 Azoplate Corp Process for the sensitization of photoconductors

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
USRE29554E (en) * 1969-06-05 1978-02-28 Addressograph-Multigraph Corporation Organic photoconductive members comprising dicyanomethylene substituted fluorene sensitizers
US4069046A (en) * 1971-02-19 1978-01-17 Xerox Corporation Polymerized vinyl carbazoles sensitized by nitro-substituted 9-dicyanomethylene fluorenes
US3864126A (en) * 1973-01-10 1975-02-04 Canon Kk Organic photoconductor with carboxy group containing fluorene or fluorore
US4066454A (en) * 1973-11-19 1978-01-03 Kabushiki Kaisha Ricoh Electrophotographic light-sensitive material containing indenothiophenone or its derivative and process of preparing indenothiophenone and its derivative
US4078927A (en) * 1973-12-13 1978-03-14 Xerox Corporation Photoconductive printing master
US4609602A (en) * 1985-03-08 1986-09-02 Xerox Corporation Photoresponsive imaging members with electron transporting layers
EP0290270A3 (en) * 1987-05-07 1990-05-09 Matsushita Electric Industrial Co., Ltd. Electrophotography photosensitive member and a method for fabricating same
US9145383B2 (en) 2012-08-10 2015-09-29 Hallstar Innovations Corp. Compositions, apparatus, systems, and methods for resolving electronic excited states
US9611246B2 (en) 2012-08-10 2017-04-04 Hallstar Innovations Corp. Compositions, apparatus, systems, and methods for resolving electronic excited states
US9765051B2 (en) 2012-08-10 2017-09-19 Hallstar Innovations Corp. Compositions, apparatus, systems, and methods for resolving electronic excited states
US9867800B2 (en) 2012-08-10 2018-01-16 Hallstar Innovations Corp. Method of quenching singlet and triplet excited states of pigments, such as porphyrin compounds, particularly protoporphyrin IX, with conjugated fused tricyclic compounds have electron withdrawing groups, to reduce generation of reactive oxygen species, particularly singlet oxygen
US9926289B2 (en) 2012-08-10 2018-03-27 Hallstar Innovations Corp. Compositions, apparatus, systems, and methods for resolving electronic excited states
US10632096B2 (en) 2012-08-10 2020-04-28 HallStar Beauty and Personal Care Innovations Company Method of quenching singlet and triplet excited states of photodegradable pigments, such as porphyrin compounds, particularly protoporphyrin IX, with conjugated fused tricyclic compounds having electron withdrawing groups, to reduce generation of singlet oxygen
US9125829B2 (en) 2012-08-17 2015-09-08 Hallstar Innovations Corp. Method of photostabilizing UV absorbers, particularly dibenzyolmethane derivatives, e.g., Avobenzone, with cyano-containing fused tricyclic compounds

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