LIGHT SENSITIVE DEVICE

Abstract

A light sensitive device including a substrate and high pass filter semiconductor nanoparticles distributed on the substrate. The substrate includes at least one photosensor, and the semiconductor nanoparticles are high pass filters in UV-visible-NIR light range. The light sensitive device has a density of the semiconductor nanoparticles per surface unit of greater than 5×10.sup.9 nanoparticles.cm.sup.−2. Also, a process for the manufacture of the light sensitive device, and an image sensor that includes the light sensitive device.

Claims

1.-19. (canceled)

20. A light sensitive device comprising a substrate and semiconductor nanoparticles distributed on the substrate according to a pattern, wherein substrate comprises at least one photosensor, wherein semiconductor nanoparticles are high pass filters in UV-visible-NIR light range, and wherein the light sensitive device comprises a density of semiconductor nanoparticles per surface unit greater than 5×10.sup.9 nanoparticles.cm.sup.−2.

21. The light sensitive device according to claim 20, wherein semiconductor nanoparticles are deposited on the substrate with a thickness of less than 10000 nm and more than 100 nm, and the volume fraction of semiconductor nanoparticles in the light sensitive device is ranging from 10% to 90%.

22. The light sensitive device according to claim 20, wherein semiconductor nanoparticles have a longest dimension less than 1 μm.

23. The light sensitive device according to claim 20, wherein semiconductor nanoparticles are inorganic.

24. The light sensitive device according to claim 23, wherein semiconductor nanoparticles are semiconductor nanocrystals comprising a material of formula M.sub.xQ.sub.yE.sub.zA.sub.w, wherein: M is selected from the group consisting of Zn, Cd, Hg, Cu, Ag, Au, Ni, Pd, Pt, Co, Fe, Ru, Os, Mn, Tc, Re, Cr, Mo, W, V, Nd, Ta, Ti, Zr, Hf, Be, Mg, Ca, Sr, Ba, Al, Ga, In, Tl, Si, Ge, Sn, Pb, As, Sb, Bi, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Cs; Q is selected from the group consisting of Zn, Cd, Hg, Cu, Ag, Au, Ni, Pd, Pt, Co, Fe, Ru, Os, Mn, Tc, Re, Cr, Mo, W, V, Nd, Ta, Ti, Zr, Hf, Be, Mg, Ca, Sr, Ba, Al, Ga, In, Tl, Si, Ge, Sn, Pb, As, Sb, Bi, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Cs; E is selected from the group consisting of O, S, Se, Te, C, N, P, As, Sb, F, Cl, Br, I; A is selected from the group consisting of O, S, Se, Te, C, N, P, As, Sb, F, Cl, Br, I; and x, y, z and w are independently a rational number from 0 to 5; x, y, z and w are not simultaneously equal to 0; x and y are not simultaneously equal to 0; z and w are not simultaneously equal to 0.

25. The light sensitive device according to claim 20, wherein semiconductor nanoparticles have a longest dimension greater than 25 nanometers.

26. The light sensitive device according to claim 20, wherein semiconductor nanoparticles are deposited with their longest dimension substantially aligned in a predetermined direction.

27. The light sensitive device according to claim 20, wherein nanoparticles are deposited with a thickness of less than 3000 nm and more than 200 nm.

28. The light sensitive device according to claim 20, wherein semiconductor nanoparticles have a cutoff wavelength in near infra-red range.

29. The light sensitive device according to claim 20, wherein semiconductor nanoparticles are composite nanoparticles comprising absorbent semiconductor nanoparticles encapsulated in a matrix.

30. The light sensitive device according to claim 20, wherein the pattern is periodic and the repetition unit of the pattern has a smallest dimension of less than 100 micrometers and comprises at least two pixels.

31. The light sensitive device according to claim 30, wherein the pattern is periodic in two dimensions.

32. The light sensitive device according to claim 29, wherein semiconductor nanoparticles on the first pixel of the at least two pixels are different from semiconductor nanoparticles on the second pixel of the at least two pixels.

33. A process for the manufacture of a light sensitive device comprising a substrate and semiconductor nanoparticles distributed on the substrate according to a pattern comprising the steps of: i)providing a film; ii) creating a surface electric potential on the film according to the pattern; iii) bringing the film in contact with a colloidal dispersion of semiconductor nanoparticles being high pass filters in UV-visible-NIR light range for a contacting time of less than 15 minutes; and iv) transferring film on a photosensor sheet, yielding said substrate; wherein the light sensitive device comprises a density of semiconductor nanoparticles per surface unit greater than 5×10.sup.9nanoparticles.cm.sup.−2.

34. The process for the manufacture of a light sensitive device according to claim 33, wherein the film is an electret film and the surface electric potential is written on the electret film.

35. The process for the manufacture of a light sensitive device according to claim 33, wherein the pattern comprises two sub-patterns, and wherein the process comprises: i)providing an electret film; ii) writing a surface electric potential on the electret film according to the first sub-pattern; iii) bringing the electret film in contact with a colloidal dispersion of semiconductor nanoparticles being high pass filters in UV-visible-NIR light range for a contacting time of less than 15 minutes; iv) drying the electret film and semiconductor nanoparticles deposited thereon to form an intermediate structure; v) writing a surface electric potential on the intermediate structure according to the second sub-pattern; vi) bringing the electret film in contact with a colloidal dispersion of semiconductor nanoparticles being high pass filters in UV-visible-NIR light range and different from those used in step iii) for a contacting time of less than 15 minutes; and vii) transferring film on a photosensor sheet, yielding said substrate.

36. The process for the manufacture of a light sensitive device according to claim 33, wherein the surface electric potential is induced and maintained on the film during contact with colloidal dispersion.

37. The process for the manufacture of a light sensitive device according to claim 33, wherein the pattern comprises two sub-patterns, and wherein the process comprises: i)providing a film; ii) inducing a surface electric potential on the film according to the first sub-pattern; iii) bringing the film in contact with a colloidal dispersion of semiconductor nanoparticles being high pass filters in UV-visible-NIR light range for a contacting time of less than 15 minutes, while surface electric potential is maintained; iv) drying the film and semiconductor nanoparticles deposited thereon to form an intermediate structure; v) inducing a surface electric potential on the intermediate structure according to the second sub-pattern; vi) bringing the film in contact with a colloidal dispersion of semiconductor nanoparticles being high pass filters in UV-visible-NIR light range and different from those used in step iii) for a contacting time of less than 15 minutes, while surface electric potential is maintained; and vii) transferring film on a photosensor sheet, yielding said substrate.

38. A process for the manufacture of a light sensitive device comprising a substrate and semiconductor nanoparticles distributed on the substrate according to a pattern comprising the steps of: i)providing a film or a substrate comprising at least one photosensor; ii) ink-jetting a colloidal dispersion of semiconductor nanoparticles being high pass filters in UV-visible-NIR light range on the film or substrate according to the pattern; and iii) optionally, transferring film on a photosensor sheet, yielding a substrate comprising at least one photosensor; wherein the light sensitive device comprises a density of semiconductor nanoparticles per surface unit greater than 5×10.sup.9nanoparticles.cm.sup.−2.

39. An image sensor comprising a light sensitive device comprising a substrate and semiconductor nanoparticles distributed on the substrate according to a pattern, wherein substrate comprises at least one photosensor, wherein semiconductor nanoparticles are high pass filters in UV-visible-NIR light range, and wherein the light sensitive device comprises a density of semiconductor nanoparticles per surface unit greater than 5×10.sup.9 nanoparticles.cm.sup.−2.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0218] FIG. 1 illustrates an exploded view of a light sensitive device (1) comprising a substrate (2). Photosensors (3—represented by the symbol of a photodiode) are included in substrate (2). Semiconductor nanoparticles (not shown) are on the substrate (2), in the volume of pixel (4a) and (4c). Pixel (4b) is an area where light is incoming directly on photosensors (3), without being filtered: there are no nanoparticles in this pixel. Pixels (4a), (4b) and (4c) are aligned above photosensors.

[0219] FIG. 2 illustrates an anisotropic semiconductor nanoparticle, here a nanoplatelet, and defines aspect ratio.

[0220] FIG. 3 illustrates an aggregate of absorbent semiconductor nanoparticles (10), here nanoplatelets, encapsulated in a matrix (20).

[0221] FIG. 4 shows absorption spectrum (arbitrary unit) of nanoplatelets used in example 1 (cutoff about 500 nm between blue range and green range: dashed line, cutoff about 600 nm between green range and red range: dotted line and cutoff about 850 nm between visible range and Infra-red range: solid line) as a function of light wavelength (λ in nanometer).

EXAMPLES

[0222] The present invention is further illustrated by the following examples.

Example 1

[0223] Preparation of a Stamp:

[0224] A photolithographic mask is fabricated on a UV-blue transparent substrate to reproduce a pattern with squared pixels of 5 μm size distributed on a square lattice of period 15 μm. A silicon carrier is covered by a uniform photolithography resin and illuminated by an UV lamp producing a 350 nm light filtered by the lithography mask in order to impress the pattern on the carrier. A proper washing solution for the resin is utilized to develop the polymer and create a tridimensional motif (pixelization).

[0225] A PDMS solution is casted on this tridimensional motif and the silicon carrier, then heated at 150° C. for 24 h to assure the polymerization of the PDMS. The solidified PDMS is thus separated from the silicon carrier. The so patterned PDMS is gold covered by evaporation technique to ensure a conductive pixelated surface. The patterned and conductive PDMS substrate is now called the stamp. It consists of a planar conductive surface on which square pixels of 5 μm size and 20 μm height are distributed on a square lattice. The stamp is a square of size 5 cm.

[0226] Preparation of Film:

[0227] A 20 micrometer thick PMMA solid film is used.

[0228] Preparation of Nanoparticles Colloidal Dispersions:

[0229] A solution A comprising 10.sup.−8 mole.L.sup.−1 CdSe.sub.0.85S.sub.0.15 nanoplatelets in cyclohexane is prepared. These nanoplatelets are 25 nm long, 10 nm wide and 1.2 nm thick and have a cutoff wavelength of 500 nm.

[0230] A solution B comprising 10.sup.−8 mole.L.sup.−1 CdSe.sub.0.80S.sub.0.20/CdS nanoplatelets in cyclohexane is prepared. These nanoplatelets are 27 nm long, 12 nm wide and 5.2 nm thick (core: 1.2 nm; shell: 2 nm) and have a cutoff wavelength of 600 nm.

[0231] A solution C comprising 10.sup.−8 mole.L.sup.−1 HgTe 3 monolayers nanoplatelets in cyclohexane is prepared. These nanoplatelets are 100 nm long, 200 nm wide and 1.1 nm thick and have a cutoff wavelength of 880 nm.

[0232] Absorption spectra of nanoparticles from solutions A, B and C are shown on FIG. 4.

[0233] Preparation of Light Sensitive Device and Image Sensor:

[0234] The film is put in contact with the stamp. A voltage of 50 V is applied for 1 minute in order to create permanent electrical polarization in the PMMA layer (electret material) only in correspondence with the pixels of the stamp.

[0235] To maintain stable the charges on the electret, humidity level of the environment is kept below 50%.

[0236] Electrically polarized PMMA film is dipped in solution A for 10 seconds then rinsed by a clean solvent and dried by a gentle flux of nitrogen.

[0237] Using a microscopic technique of alignment, the stamp is then again placed on the already red pixelated film, with pixels of the stamp defining a second pixel on the film (different from the blue cutting pixel) according to the original pattern chosen and in correspondence with photodiodes. A voltage of 50 V is applied again for 1 minute in order to create permanent electrical polarization in the PMMA film only in correspondence with the pixels of the stamp, i.e. in correspondence with areas free of nanoparticles.

[0238] Electrically polarized PMMA film is dipped in solution B for 10 seconds then rinsed by a clean solvent and dried by a gentle flux of nitrogen.

[0239] Using the same microscopic technique of alignment, the stamp is then again placed on the already red/green pixelated film, with pixels of the stamp defining a third pixel on the substrate (different from the blue and green cutting pixels) according to the original pattern chosen and in correspondence with photodiodes. A voltage of 50 V is applied again for 1 minute in order to create permanent electrical polarization in the PMMA film only in correspondence with the pixels of the stamp.

[0240] Electrically polarized PMMA film is dipped in solution C for 10 seconds then rinsed by a clean solvent and dried by a gentle flux of nitrogen.

[0241] The three steps are designed in such a way that an area of the film is not treated: light incoming on this area is not filtered at all.

[0242] Last, film is transferred on a photosensors sheet, so that photosensors are aligned with pixels of nanoparticles. An optically clear UV curable adhesive is used to maintain film. In addition, this adhesive provides with UV-A absorption.

[0243] An array of photodiodes coated with a 20 micrometer PMMA layer with square pixels of 5 μm size and three different types of particles (500 nm, 600 nm and 880 nm cutoff wavelength particles) distributed on a square lattice of period 15 μm is obtained, forming an light sensing device sensor suitable for measurements of visible light colour components as well as NIR component. Indeed, for each group of four photodiodes, one signal corresponds to the whole visible spectrum (UV-A filtered out by adhesive), one signal corresponds to green-red-NIR spectrum, one signal corresponds to red-NIR spectrum and one signal corresponds to NIR spectrum. By difference between signals, colour components of incoming light is therefore determined.

[0244] An image sensor is prepared with this light sensing device using well known methods of microelectronic industry.

[0245] Example 1-2

[0246] Example 1 is reproduced, except that semiconductor nanoplatelets are changed as listed in Table I.

TABLE-US-00001 TABLE I Colloidal dispersions of semiconductor nanoplatelets used for deposition on electret film (MLs refers to the number of monolayers of material). Nanoplatelets Nanoplatelets dimensions Cut-off λ Deposition / L (nm) W (nm) T (nm) / / CdSe.sub.0.40S.sub.0.60 5MLs 27 18 1.5 500 nm observed CdSe 4MLs 8 4 1.2 500 nm observed CdSe.sub.0.15S.sub.0.85—Br 5MLs 30 20 1.5 500 nm observed CdSe 8MLs 50 9 2.4 623 nm observed CdSe—Br 6MLs 21 16 1.8 600 nm observed HgTe—Br 2MLs 120 180 0.8 880 nm observed HgSe—Br 4MLs 100 250 1.6 880 nm observed Hg.sub.0.50Cd.sub.0.50Te 4MLs 120 200 1.6 880 nm observed CORE/CROWN NANOPLATELETS CdSe/CdS 6MLs 24 18 1.8 600 nm observed

Example 2

[0247] Example 1 is reproduced, except that composite nanoparticles comprising absorbent nanoparticles encapsulated in a matrix are used.

[0248] Example 2-1: Absorbent Nanoplatelets in SiO.sub.2 Matrix.

[0249] First, 500 μL of colloidal CdSe.sub.0.85S.sub.0.15 4 monolayers nanoplatelets in a basic aqueous solution is prepared. These nanoplatelets are 25 nm long, 10 nm wide and 1.2 nm thick and have a cutoff wavelength about 500 nm. 10 μL of a hydrolyzed basic aqueous solution of tetraethylorthosilicate (TEOS) at 0.13 mole.L.sup.−1 is added to colloidal nanoplatelets and gently mixed. The liquid mixture is sprayed towards a tube furnace heated at a temperature of 300° C. with a nitrogen flow. Composite nanoparticles are collected at the surface of a filter.

[0250] A solution E comprising 10.sup.−6 mole.L.sup.−1 CdSe.sub.0.85S.sub.0.15 4 monolayers of composite nanoparticles in heptane is prepared.

[0251] Example 2-2: Absorbent Nanoplatelets in Al.sub.2O.sub.3 Matrix.

[0252] First, 500 μL of colloidal CdSe.sub.0.85S.sub.0.15 4 monolayers nanoplatelets in heptane is prepared. These nanoplatelets are 25 nm long, 10 nm wide and 1.2 nm thick and have a cutoff wavelength about 500 nm. 5 mL of a solution of aluminium tri-sec butoxide at 0.25 mole.L.sup.−1 in heptane is added to colloidal nanoplatelets and gently mixed. A basic aqueous solution is prepared separately. The two liquids are sprayed simultaneously towards a tube furnace heated at a temperature of 300° C. with a nitrogen flow. Composite nanoparticles are collected at the surface of a filter.

[0253] A solution F comprising 10.sup.−6 mole.L.sup.−1 CdSe.sub.0.85S.sub.0.15 4 monolayers of composite nanoparticles in heptane is prepared.

[0254] Example 2-3: Absorbent Nanoplatelets in Organic Matrix.

[0255] First, 500 μL of colloidal CdSe.sub.0.85S.sub.0.15 4 monolayers nanoplatelets in heptane is prepared. These nanoplatelets are 25 nm long, 10 nm wide and 1.2 nm thick and have a cutoff wavelength about 500 nm. 200 mg of PMMA (PolyMethylMethAcrylate, 120 kDa) is solubilized in 10 mL of toluene, then mixed with colloidal solution. The liquid mixture was sprayed towards a tube furnace heated at 200° C. with a nitrogen flow. Composite nanoparticles are collected at the surface of a filter.

[0256] A solution G comprising 10.sup.−6 mole.L.sup.−1 CdSe.sub.0.85S.sub.0.15 4 monolayers of composite nanoparticles in heptane is prepared.

[0257] Example 2-4: Absorbent Nanoparticles in Al.sub.2O.sub.3 Matrix.

[0258] First, 4 mL InP/ZnSe.sub.0.50S.sub.0.50/ZnS nanoparticles in heptane is prepared. These nanoparticles have a diameter of 9.5 nm (core of diameter: 3.5 nm; first shell thickness: 2 nm; second shell thickness: 1 nm) and have a cutoff wavelength about 600 nm. 5 mL of a solution of aluminium tri-sec butoxide at 0.25 mole.L.sup.−1 is added to colloidal nanoplatelets and gently mixed. A basic aqueous solution is prepared separately. The two liquids are sprayed simultaneously towards a tube furnace heated at a temperature of 300° C. with a nitrogen flow. Composite nanoparticles are collected at the surface of a filter.

[0259] A solution of 50 mg of composite nanoparticles in 9 mL of tetrahydrofuran is prepared. 13 μL of octanoic acid, 60 μL of a 4-(dimethylamino)pyridine stock solution (1 mg/100 μL of dimethylformamide), 6 μL of triethylamine and 2 μL of benzoyl chloride are added. The mixture is then left to mix at room temperature over 48 hours, yielding composite nanoparticles with surface modification allowing for better dispersion in hydrocarbons solvents.

[0260] A solution H comprising 10.sup.−6 mole.L.sup.−1 InP/ZnSe.sub.0.50S.sub.0.50/ZnS of composite nanoparticles in heptane is prepared.

[0261] Example 2-5: Absorbent Nanoparticles in Organic Matrix

[0262] First, 100 μL of InP/ZnSe.sub.0.50S.sub.0.50/ZnS nanoparticles in heptane is prepared. These nanoparticles have a diameter of 9.5 nm (core of diameter: 3.5 nm; first shell thickness: 2 nm; second shell thickness: 1 nm) and have a cutoff wavelength about 600 nm. 200 mg of PMMA (PolyMethylMethAcrylate, 120 kDa) is solubilized in 10 mL of toluene, then mixed with colloidal solution. The liquid mixture was sprayed towards a tube furnace heated at 200° C. with a nitrogen flow. Composite nanoparticles are collected at the surface of a filter.

[0263] A solution I comprising 10.sup.−6 mole.L.sup.−1 InP/ZnSe.sub.0.50S.sub.0.50/ZnS of composite nanoparticles in heptane is prepared.

[0264] After dipping of electrically polarized PMMA film in solution E, F, G, H or I instead of solution A, composite nanoparticle deposition is observed as for example 1, but thickness of layer of composite nanoparticles deposited is larger than thickness of layer of non-encapsulated nanoparticles.

[0265] Example 2-6: Absorbent Nanoparticles in Matrix

[0266] Example 1 is reproduced with composite nanoparticles comprising absorbent nanoparticles encapsulated in a matrix listed in Table II.

TABLE-US-00002 TABLE II Colloidal dispersions of composite particles used for deposition on electret film. Dimensions Composite particle Nanoparticles (nm) Matrix dimensions Cut-off λ Deposition QUANTUM DOTS IN MATRIX InP/ZnSe.sub.0.50S.sub.0.50/ZnS 7.2 Al.sub.2O.sub.3 200 nm 500 nm observed InP/GaP 5 SiO.sub.2 500 nm 500 nm observed Cd.sub.3P.sub.2 2 PMMA 450 nm 500 nm observed Cd.sub.0.20Zn.sub.0.80Se/ZnSe/ZnS 15 Al.sub.2O.sub.3 150 nm 600 nm observed CdSe/Zn.sub.0.50Cd.sub.0.50Se/ZnSe 7 SiO.sub.2 350 nm 600 nm observed InP/ZnSe 5 PMMA 200 nm 600 nm observed Ag.sub.2S 2 PMMA 250 nm 880 nm observed Cd.sub.3P.sub.2/ZnS 5 SiO.sub.2 175 nm 880 nm observed Cd.sub.3As.sub.2/ZnS 10 Al.sub.2O.sub.3 215 nm 880 nm observed NANOPLATELETS IN MATRIX (L*W*T) CdSe.sub.0.40S.sub.0.60 5MLs 27*18*1.5 Al.sub.2O.sub.3 200 nm 500 nm observed CdSe 4MLs 8*4*1.2 SiO.sub.2 500 nm 500 nm observed CdSe.sub.0.15S.sub.0.85—Br 5MLs 30*20*1.5 PMMA 450 nm 500 nm observed CdSe 8MLs 50*9*2.4 Al.sub.2O.sub.3 350 nm 623 nm observed CdSe—Br 6MLs 21*16*1.8 SiO.sub.2 150 nm 600 nm observed HgTe—Br 2MLs 120*180*0.8 PMMA 200 nm 600 nm observed HgSe—Br 4MLs 100*250*1.6 PMMA 215 nm 880 nm observed Hg.sub.0.50Cd.sub.0.50Te 4MLs 120*200*1.6 SiO.sub.2 175 nm 880 nm observed CdSe.sub.0.40S.sub.0.60 5MLs 27*18*1.5 Al.sub.2O.sub.3 250 nm 880 nm observed

Example 3

[0267] Preparation of Nanoparticles Colloidal Dispersions:

[0268] A solution A comprising 10.sup.−8 mole.L.sup.−1 CdSe.sub.0.85S.sub.0.15 nanoplatelets in cyclohexane is prepared. These nanoplatelets are 25 nm long, 10 nm wide and 1.2 nm thick and have a cutoff wavelength of 500 nm.

[0269] A solution B comprising 10.sup.−8 mole.L.sup.−1 CdSe.sub.0.80S.sub.0.20/CdS nanoplatelets in cyclohexane is prepared. These nanoplatelets are 27 nm long, 12 nm wide and 5.2 nm thick (core: 1.2 nm; shell: 2 nm) and have a cutoff wavelength of 600 nm.

[0270] A solution C comprising 10.sup.−8 mole.L.sup.−1 HgTe 3 monolayers nanoplatelets in cyclohexane is prepared. These nanoplatelets are 100 nm long, 200 nm wide and 1.1 nm thick and have a cutoff wavelength of 880 nm.

[0271] Preparation of Light Sensitive Device and Image Sensor:

[0272] A sheet of photodiodes is provided. Photodiodes are distributed on 8 concentric circles of radius increasing by steps of 25 nm. Each circle being chopped in angular section of 15°, called sectors.

[0273] Solution A is ink-jetted on photodiodes corresponding to one sector. Solution B is ink-jetted on photodiodes corresponding to next sector (clockwise). Solution C is ink-jetted on photodiodes corresponding to next sector (clockwise). Next sector (clockwise) is left untreated. This process is repeated three times, yielding a circular light sensitive device of 400 micrometer diameter, with coloured sectors organized as a pie.

[0274] As four sectors have the same characteristics, this device allows for redundant analysis of signal.

Example 4

[0275] Example 3 is reproduced, except that nanoparticles are ink-jetted on each circle so that solution A, solution B, solution C and empty are deposited successively in each sector.

Example 5

[0276] Example 1 is reproduced, except that substrate and preparation of light sensitive device are changed.

[0277] Film is a 50 μm thick square glass slide of size 5 cm. Film is held horizontally.

[0278] The stamp is placed below the film and in contact with the substrate. A voltage of 50 V is applied in order to induce electrical polarization in the film only in correspondence with the pixels of the stamp.

[0279] While voltage is applied, a layer of solution A is poured on the top side of film and voltage is maintained for 10 seconds then shut off. Stamp is removed from bottom side of film and excess solution A is removed. Film is then rinsed by a clean solvent and dried by a gentle flux of nitrogen.

[0280] Using a microscopic technique of alignment, the stamp is then again placed below the already red pixelated film, with pixels of the stamp defining a second pixel on the film (different from the blue cutting pixel) according to the original periodic patterning chosen. A voltage of 50 V is applied in order to induce electrical polarization in correspondence with the pixels of the stamp.

[0281] While voltage is applied, a layer of solution B is poured on the top side of film and voltage is maintained for 10 seconds then shut off. Stamp is removed from bottom side of film and excess solution B is removed. Film is then rinsed by a clean solvent and dried by a gentle flux of nitrogen.

[0282] Using the same microscopic technique of alignment, the stamp is then again placed below the already red/green pixelated film, with pixels of the stamp defining a third pixel on the substrate (different from the blue and green cutting pixels) according to the original periodic patterning chosen. A voltage of 50 V is applied in order to induce electrical polarization in correspondence with the pixels of the stamp.

[0283] While voltage is applied, a layer of solution C is poured on the top side of film and voltage is maintained for 10 seconds then shut off. Stamp is removed from bottom side of film and excess solution C is removed. Film is then rinsed by a clean solvent and dried by a gentle flux of nitrogen.

[0284] Last, film is transferred on a photosensors sheet, so that photosensors are aligned with pixels of nanoparticles. An optically clear UV curable adhesive is used to maintain film.

[0285] In addition, this adhesive provides with UV-A absorption.

Example 6

[0286] Example 5 is reproduced, but using composite nanoparticles of example 2-4 (solutions H) and example 2-5 (solutions I).

Comparative Example C1

[0287] Example 1 is reproduced, except that nanoparticles are changed.

[0288] A solution C-A comprising 10.sup.−8 mole.L.sup.−1 CdSe nanoparticles in cyclohexane is prepared. These nanoparticles are spherical (aspect ratio of 1) with a diameter of 2.5 nm and have a cutoff wavelength of 500 nm.

[0289] A solution C-B comprising 10.sup.−8 mole.L.sup.−1 CdTe nanoparticles in cyclohexane is prepared. These nanoparticles are spherical (aspect ratio of 1) with a diameter of 2.5 nm have a cutoff wavelength of 600 nm.

[0290] After dipping of substrate with electrically polarized PMMA layer in solution C-A instead of solution A, no significant nanoparticle deposition is observed: isolated nanoparticles are found on the substrate, but they do not form a layer of nanoparticles. No selective deposition on the pattern occurs.

[0291] After dipping of substrate with electrically polarized PMMA layer in solution C-B instead of solution B, no significant nanoparticle deposition is observed: isolated nanoparticles are found on the substrate, but they do not form a layer of nanoparticles. No selective deposition on the pattern occurs