Organic Compound of Formula (I) for Use in Organic Electronic Devices, a Composition Comprising a Compound of Formula (IV) and at Least One Compound of Formula (IVa) to (IVd), an Organic Semiconductor Layer Comprising the Compound or Composition, an Organic Electronic Device Comprising the Organic Semiconductor Layer, and a Display Device Comprising the Organic Electronic Device

Abstract

The present invention relates to a compound of formula (I) for use in organic electronic devices, a composition comprising a compound of formula (IV) and at least one compound of formula (IVa) to (IVd), an organic semiconductor layer comprising the compound or composition, an organic electronic device comprising the organic semiconductor layer, and a display device comprising the organic electronic device.

##STR00001##

Claims

1. A compound of formula (I) ##STR00449## whereby A.sup.1 is selected from formula (II) ##STR00450## X.sup.1 is selected from CR.sup.1 or N; X.sup.2 is selected from CR.sup.2 or N; X.sup.3 is selected from CR.sup.3 or N; X.sup.4 is selected from CR.sup.4 or N; X.sup.5 is selected from CR.sup.5 or N; R.sup.1 and R.sup.5 (if present) are independently selected from CN, NO.sub.2, CF.sub.3, halogen, Cl, F, H or D; R.sup.2, R.sup.3, and R.sup.4 (if present) are independently selected from CN, NO.sub.2, partially fluorinated or perfluorinated C.sub.1 to C.sub.8 alkyl, halogen, Cl, F, H or D; whereby when any of R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 is present, then the corresponding X.sup.1, X.sup.2, X.sup.3, X.sup.4 and X.sup.5 is not N; with the proviso that at least one of R.sup.2 and R.sup.4 is present and independently selected from H or D; at least three of R.sup.1, R.sup.2, R.sup.3, R.sup.4 or R.sup.5 are present, and at least one of R.sup.1, R.sup.2, R.sup.3, R.sup.4 or R.sup.5 is not H or D; A.sup.2 and A.sup.3 are independently selected from formula (III) ##STR00451## wherein Ar is independently selected from substituted or unsubstituted C.sub.6 to C.sub.18 aryl and substituted or unsubstituted C.sub.2 to C.sub.18 heteroaryl, wherein the substituents on Ar are independently selected from CN, NO.sub.2, partially or perfluorinated C.sub.1 to C.sub.6 alkyl, halogen, Cl, F, D; R′ is selected from Ar, substituted or unsubstituted C.sub.6 to C.sub.18 aryl or C.sub.3 to C.sub.18 heteroaryl, partially fluorinated or perfluorinated C.sub.1 to C.sub.8 alkyl, halogen, F or CN; wherein the asterix “*” denotes the binding position; and wherein A.sup.1, A.sup.2 and A.sup.3 are selected in a way that A.sup.1 differs from at least one of A.sup.2 or A.sup.3.

2. The compound of claim 1, selected of the formula (IV) ##STR00452## whereby B.sup.1 is selected from formula (V) ##STR00453## B.sup.3 and B.sup.5 are Ar and B.sup.2, B.sup.4 and B.sup.6 are R′.

3. The compound of claim 1, whereby the compound comprises less than nine CN groups.

4. The compound of claim 1, whereby R.sup.3 is present and R.sup.3 is selected from CN, NO.sub.2, partially fluorinated or perfluorinated C.sub.1 to C.sub.8 alkyl, halogen, Cl, or F.

5. The compound of claim 1, whereby less than four of R.sup.1, R.sup.2, R.sup.3, R.sup.4 or R.sup.5 if present are H or D.

6. The compound of claim 1, whereby the calculated LUMO of the compound is in the range of ≤−4.35 eV to ≥−5.75 eV.

7. The compound of claim 1, whereby a total of 0, 1, or 2 of X.sup.1, X.sup.2, X.sup.3, X.sup.4 and X.sup.5 are N.

8. The compound of claim 1, whereby at least two or more of R.sup.1 to R.sup.5 are not H or D.

9. A composition comprising a compound of formula (IV) and at least one compound of formula (IVa) to (IVd) ##STR00454##

10. An organic semiconductor layer, whereby the organic semiconductor layer comprises a compound of claim 1.

11. An organic electronic device comprising an anode layer, a cathode layer, and at least one organic semiconductor layer, wherein the at least one organic semiconductor layer is arranged between the anode layer and the cathode layer, and wherein the at least one organic semiconductor layer is the organic semiconductor layer according to claim 10.

12. The organic electronic device of claim 11, whereby the organic electronic device further comprises at least one photoactive layer, wherein the at least one photoactive layer is arranged between the anode layer and the cathode layer and at least one of the at least one organic semiconductor layers is arranged between the anode layer and the at least one photoactive layer.

13. The organic electronic device of claim 11, whereby the photoactive layer is a light emitting layer.

14. The organic electronic device of claim 11, whereby the organic electronic device is an electroluminescent device.

15. A display device comprising an organic electronic device according to claim 11.

Description

DESCRIPTION OF THE DRAWINGS

[0252] The aforementioned components, as well as the claimed components and the components to be used in accordance with the invention in the described embodiments, are not subject to any special exceptions with respect to their size, shape, material selection and technical concept such that the selection criteria known in the pertinent field can be applied without limitations.

[0253] Additional details, characteristics and advantages of the object of the invention are disclosed in the dependent claims and the following description of the respective figures which in an exemplary fashion show preferred embodiments according to the invention. Any embodiment does not necessarily represent the full scope of the invention, however, and reference is made therefore to the claims and herein for interpreting the scope of the invention. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are intended to provide further explanation of the present invention as claimed.

[0254] FIG. 1 is a schematic sectional view of an organic electronic device, according to an exemplary embodiment of the present invention;

[0255] FIG. 2 is a schematic sectional view of an organic light-emitting diode (OLED), according to an exemplary embodiment of the present invention;

[0256] FIG. 3 is a schematic sectional view of an OLED, according to an exemplary embodiment of the present invention.

[0257] FIG. 4 is a schematic sectional view of an OLED, according to an exemplary embodiment of the present invention.

[0258] FIG. 5 is a schematic sectional view of an OLED, according to an exemplary embodiment of the present invention.

[0259] Hereinafter, the figures are illustrated in more detail with reference to examples. However, the present disclosure is not limited to the following figures.

[0260] Herein, when a first element is referred to as being formed or disposed “on” or “onto” a second element, the first element can be disposed directly on the second element, or one or more other elements may be disposed there between. When a first element is referred to as being formed or disposed “directly on” or “directly onto” a second element, no other elements are disposed there between.

[0261] FIG. 1 is a schematic sectional view of an organic electronic device 100, according to an exemplary embodiment of the present invention. The organic electronic device 100 includes a substrate 110, an anode layer 120 and a hole injection layer (HIL) 130 which may comprise a compound of formula (I). The HIL 130 is disposed on the anode layer 120. Onto the HIL 130, a photoactive layer (PAL) 170 and a cathode layer 190 are disposed.

[0262] FIG. 2 is a schematic sectional view of an organic light-emitting diode (OLED) 100, according to an exemplary embodiment of the present invention. The OLED 100 includes a substrate 110, an anode layer 120 and a hole injection layer (HIL) 130 which may comprise a compound of formula (I). The HIL 130 is disposed on the anode layer 120. Onto the HIL 130, a hole transport layer (HTL) 140, an emission layer (EML) 150, an electron transport layer (ETL) 160, an electron injection layer (EIL) 180 and a cathode layer 190 are disposed. Instead of a single electron transport layer 160, optionally an electron transport layer stack (ETL) can be used.

[0263] FIG. 3 is a schematic sectional view of an OLED 100, according to another exemplary embodiment of the present invention. FIG. 3 differs from FIG. 2 in that the OLED 100 of FIG. 3 comprises an electron blocking layer (EBL) 145 and a hole blocking layer (HBL) 155.

[0264] Referring to FIG. 3, the OLED 100 includes a substrate 110, an anode layer 120, a hole injection layer (HIL) 130 which may comprise a compound of formula (I), a hole transport layer (HTL) 140, an electron blocking layer (EBL) 145, an emission layer (EML) 150, a hole blocking layer (HBL) 155, an electron transport layer (ETL) 160, an electron injection layer (EIL) 180 and a cathode layer 190.

[0265] FIG. 4 is a schematic sectional view of an organic electronic device 100, according to an exemplary embodiment of the present invention. The organic electronic device 100 includes a substrate 110, an anode layer 120 that comprises a first anode sub-layer 121, a second anode sub-layer 122 and a third anode sub-layer 123, and a hole injection layer (HIL) 130. The HIL 130 is disposed on the anode layer 120. Onto the HIL 130, an hole transport layer (HTL) 140, a first emission layer (EML) 150, a hole blocking layer (HBL) 155, an electron transport layer (ETL) 160, and a cathode layer 190 are disposed. The hole injection layer 130 may comprise a compound of formula (I).

[0266] FIG. 5 is a schematic sectional view of an organic electronic device 100, according to an exemplary embodiment of the present invention. The organic electronic device 100 includes a substrate 110, an anode layer 120 that comprises a first anode sub-layer 121, a second anode sub-layer 122 and a third anode sub-layer 123, and a hole injection layer (HIL) 130. The HIL 130 is disposed on the anode layer 120. Onto the HIL 130, a hole transport layer (HTL) 140, an electron blocking layer (EBL) 145, a first emission layer (EML) 150, a hole blocking layer (HBL) 155, an electron transport layer (ETL) 160, an electron injection layer (EIL) 180 and a cathode layer 190 are disposed. The hole injection layer 130 may comprise a compound of formula (I).

[0267] While not shown in FIG. 1 to FIG. 5, a capping and/or sealing layer may further be formed on the cathode layer 190, in order to seal the organic electronic device 100. In addition, various other modifications may be applied thereto.

[0268] Hereinafter, one or more exemplary embodiments of the present invention will be described in detail with, reference to the following examples. However, these examples are not intended to limit the purpose and scope of the one or more exemplary embodiments of the present invention.

DETAILED DESCRIPTION

[0269] The invention is furthermore illustrated by the following examples which are illustrative only and non-binding.

[0270] Compounds of formula (I) may be prepared as described in EP2180029A1 and WO2016097017A1.

Calculated HOMO and LUMO

[0271] The HOMO and LUMO are calculated with the program package TURBOMOLE V6.5 (TURBOMOLE GmbH, Litzenhardtstrasse 19, 76135 Karlsruhe, Germany). The optimized geometries and the HOMO and LUMO energy levels of the molecular structures are determined by applying the hybrid functional B3LYP with a 6-31G* basis set in the gas phase. If more than one conformation is viable, the conformation with the lowest total energy is selected.

Melting Point

[0272] The melting point (Tm) is determined as peak temperatures from the DSC curves of the above TGA-DSC measurement or from separate DSC measurements (Mettler Toledo DSC822e, heating of samples from room temperature to completeness of melting with heating rate 10 K/min under a stream of pure nitrogen. Sample amounts of 4 to 6 mg are placed in a 40 μL Mettler Toledo aluminum pan with lid, a <1 mm hole is pierced into the lid).

Glass Transition Temperature

[0273] The glass transition temperature (Tg) is measured under nitrogen and using a heating rate of 10 K per min in a Mettler Toledo DSC 822e differential scanning calorimeter as described in DIN EN ISO 11357, published in March 2010.

Thermogravimetric Analysis

[0274] The term “TGA5%” denotes the temperature at which 5% weight loss occurs during thermogravimetric analysis and is measured in ° C.

[0275] The TGA5% value may be determined by heating a 9-11 mg sample in a thermogravimetric analyser at a heating rate of 10 K/min in an open 100 μL aluminium pan, under a stream of nitrogen at a flow rate of 20 mL/min in the balance area and of 30 mL/min in the oven area.

[0276] The TGA5% value may provide an indirect measure of the volatility and/or decomposition temperature of a compound. In first approximation, the higher the TGA5% value the lower is the volatility of a compound and/or the higher the decomposition temperature.

[0277] According to one embodiment, the TGA5% value of compound of formula (I) is selected in the range of ≥280° C. and ≤390° C.; preferably of ≥290° C. and ≤380° C., also preferred of ≥295° C. and ≤370° C.

General Procedure for Fabrication of OLEDs

[0278] For Examples 1 to 12 and comparative example 1 and 2 in Table 3, a glass substrate with an anode layer comprising a first anode sub-layer of 120 nm Ag, a second anode sub-layer of 8 nm ITO and a third anode sub-layer of 10 nm ITO was cut to a size of 50 mm×50 mm×0.7 mm, ultrasonically washed with water for 60 minutes and then with isopropanol for 20 minutes. The liquid film was removed in a nitrogen stream, followed by plasma treatment, to prepare the anode layer. The plasma treatment was performed in nitrogen atmosphere or in an atmosphere comprising 98 vol.-% nitrogen and 2 vol.-% oxygen.

[0279] Then, Biphenyl-4-yl(9,9-diphenyl-9H-fluoren-2-yl)-[4-(9-phenyl-9H-carbazol-3-yl) phenyl]-amine as matrix compound and compound of formula (I) were co-deposited in vacuum on the anode layer, to form a hole injection layer (HIL) having a thickness of 10 nm. The percentage compound of formula (I) in the HIL can be seen in Table 3.

[0280] Then, Biphenyl-4-yl(9,9-diphenyl-9H-fluoren-2-yl)-[4-(9-phenyl-9H-carbazol-3-yl) phenyl]-amine was vacuum deposited on the HIL, to form a HTL having a thickness of 122 nm.

[0281] Then N-([1,1′-biphenyl]-4-yl)-9,9-diphenyl-N-(4-(triphenylsilyl)phenyl)-9H-fluoren-2-amine (CAS 1613079-70-1) for comparative example 2 and examples 1 to 3, and N-(4-(dibenzo[b,d]furan-4-yl)phenyl)-N-(4-(9-phenyl-9H-fluoren-9-yl)phenyl)-[1,1′-biphenyl]-4-amine for comparative example 1, was vacuum deposited on the HTL, to form an electron blocking layer (EBL) having a thickness of 5 nm.

[0282] Then 97 vol.-% H09 (Sun Fine Chemicals, Korea) as EMIL host and 3 vol.-% BD200 (Sun Fine Chemicals, Korea) as fluorescent blue emitter dopant were deposited on the EBL, to form a blue-emitting first emission layer (EMIL) with a thickness of 20 nm.

[0283] Then a hole blocking layer was formed with a thickness of 5 nm by depositing 2-(3′-(9,9-dimethyl-9H-fluoren-2-yl)-[1,1′-biphenyl]-3-yl)-4,6-diphenyl-1,3,5-triazine on the emission layer EML.

[0284] Then the electron transporting layer having a thickness of 31 nm was formed on the hole blocking layer by co-depositing 50 wt.-% 4′-(4-(4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)naphthalen-1-yl)-[1,1′-biphenyl]-4-carbonitrile and 50 wt.-% of LiQ.

[0285] Then an electron injection layer having a thickness of 2 nm was formed on the ETL by depositing Ytterbium.

[0286] Then Ag:Mg (90:10 vol.-%) was evaporated at a rate of 0.01 to 1 Å/s at 10-7 mbar to form a cathode layer with a thickness of 13 nm on the electron injection layer.

[0287] Then, Biphenyl-4-yl(9,9-diphenyl-9H-fluoren-2-yl)-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-amine was deposited on the cathode layer to form a capping layer with a thickness of 75 nm.

[0288] The OLED stack is protected from ambient conditions by encapsulation of the device with a glass slide. Thereby, a cavity is formed, which includes a getter material for further protection. To assess the performance of the inventive examples compared to the prior art, the current efficiency is measured at 20° C. The current-voltage characteristic is determined using a Keithley 2635 source measure unit, by sourcing a voltage in V and measuring the current in mA flowing through the device under test. The voltage applied to the device is varied in steps of 0.1V in the range between 0V and 10V. Likewise, the luminance-voltage characteristics and CIE coordinates are determined by measuring the luminance in cd/m.sup.2 using an Instrument Systems CAS-140CT array spectrometer (calibrated by Deutsche Akkreditierungsstelle (DAkkS)) for each of the voltage values. The cd/A efficiency at 10 mA/cm2 is determined by interpolating the luminance-voltage and current-voltage characteristics, respectively.

[0289] In bottom emission devices, the emission is predominately Lambertian and quantified in percent external quantum efficiency (EQE). To determine the efficiency EQE in % the light output of the device is measured using a calibrated photodiode at 10 mA/cm2.

[0290] In top emission devices, the emission is forward directed, non-Lambertian and also highly dependent on the micro-cavity. Therefore, the efficiency EQE will be higher compared to bottom emission devices. To determine the efficiency EQE in % the light output of the device is measured using a calibrated photodiode at 10 mA/cm.sup.2.

[0291] Lifetime LT of the device is measured at ambient conditions (20° C.) and 30 mA/cm.sup.2, using a Keithley 2400 sourcemeter, and recorded in hours.

[0292] The brightness of the device is measured using a calibrated photo diode. The lifetime LT is defined as the time till the brightness of the device is reduced to 97% of its initial value.

[0293] The increase in operating voltage U over time “U(100-1 h)” is measured by determining the difference in operating voltage at 30 mA/cm.sup.2 after 1 hour and after 100 hours.

Technical Effect of the Invention

[0294] In Table 1 are shown LUMO levels for Examples A1 to A57. LUMO levels were calculated with the program package TURBOMOLE V6.5 (TURBOMOLE GmbH, Litzenhardtstrasse 19, 76135 Karlsruhe, Germany) by applying the hybrid functional B3LYP with a 6-31G* basis set in the gas phase.

TABLE-US-00002 TABLE 1 Calculated LUMO level of compounds of formulas (I) LUMO Compound A.sup.1 A.sup.2 A.sup.3 [eV] A1  [00244] [00245] [00246] −5.00 A2  [00247] [00248] [00249] −5.12 A3  [00250] [00251] [00252] −4.98 A4  [00253] [00254] [00255] −5.18 A5  [00256] [00257] [00258] −5.36 A6  [00259] [00260] [00261] −4.91 A7  [00262] [00263] [00264] −5.05 A8  [00265] [00266] [00267] −4.86 A9  [00268] [00269] [00270] −5.10 A10 [00271] [00272] [00273] −5.03 A11 [00274] [00275] [00276] −5.05 A12 [00277] [00278] [00279] −5.00 A13 [00280] [00281] [00282] −5.22 A14 [00283] [00284] [00285] −4.91 A15 [00286] [00287] [00288] −5.10 A16 [00289] [00290] [00291] −4.91 A17 [00292] [00293] [00294] −5.02 A18 [00295] [00296] [00297] −5.13 A19 [00298] [00299] [00300] −5.2  A20 [00301] [00302] [00303] −4.94 A21 [00304] [00305] [00306] −5.35 A22 [00307] [00308] [00309] −5.04 A23 [00310] [00311] [00312] −5.10 A24 [00313] [00314] [00315] −4.84 A25 [00316] [00317] [00318] −5.25 A26 [00319] [00320] [00321] −5.16 A27 [00322] [00323] [00324] −5.23 A28 [00325] [00326] [00327] −4.97 A29 [00328] [00329] [00330] −5.37 A30 [00331] [00332] [00333] −5.01 A31 [00334] [00335] [00336] −5.16 A32 [00337] [00338] [00339] −4.91 A33 [00340] [00341] [00342] −5.32 A34 [00343] [00344] [00345] −5.08 A35 [00346] [00347] [00348] −5.19 A36 [00349] [00350] [00351] −4.94 A37 [00352] [00353] [00354] −5.35 A38 [00355] [00356] [00357] −5.04 A39 [00358] [00359] [00360] −5.17 A40 [00361] [00362] [00363] −4.92 A41 [00364] [00365] [00366] −5.33 A42 [00367] [00368] [00369] −5.11 A43 [00370] [00371] [00372] −5.25 A44 [00373] [00374] [00375] −5.12 A45 [00376] [00377] [00378] −5.18 A46 [00379] [00380] [00381] −5.33 A47 [00382] [00383] [00384] −5.28 A48 [00385] [00386] [00387] −5.34 A49 [00388] [00389] [00390] −5.09 A50 [00391] [00392] [00393] −5.16 A51 [00394] [00395] [00396] −5.23 A52 [00397] [00398] [00399] −4.97 A53 [00400] [00401] [00402] −5.37 A54 [00403] [00404] [00405] −5.02 A55 [00406] [00407] [00408] −4.83 A56 [00409] [00410] [00411] −5.17 A57 [00412] [00413] [00414] −5.15 A58 [00415] [00416] [00417] −4.93 A59 [00418] [00419] [00420] −4.92 A60 [00421] [00422] [00423] −4.82 A61 [00424] [00425] [00426] −4.83 A62 [00427] [00428] [00429] −5.17 A63 [00430] [00431] [00432] −5.16 A64 [00433] [00434] [00435] −5.12 A65 [00436] [00437] [00438] −4.99 A66 [00439] [00440] [00441] −4.91 A67 [00442] [00443] [00444] −4.73 A68 [00445] [00446] [00447] −4.98

[0295] Table 2 shows the physical properties of compounds of formula (I) and comparative compound 1, used in examples 1 to 3 and comparative example 1 and 2. For the inventive compounds, reference is made to the structural definitions in table 1.

[0296] Comparative compound 1 (CC1) has the following structure:

##STR00448##

TABLE-US-00003 TABLE 2 Physical properties of compounds of formula (I) and comparative compound 1 Compound Tg/° C. Tm/° C. TGA5%/° C. DFT LUMO/eV Comparative 65 210 264 −4.58 compound 1 Inventive 91 267 319 −4.95 compound 1 (A3) Inventive n.d. n.d. 309 −4.99 compound 2 (A65) Inventive n.d. n.d. 304 −4.83 compound 3 (A61) Inventive n.d. 217 297 −4.82 compound 4 (A60) Inventive n.d. n.d. 321 −4.92 compound 5 (A59) Inventive n.d. n.d. 321 −4.93 compound 6 (A58) Inventive n.d. 227 324 −4.91 compound 7 (A66) Inventive n.d. 213 387 −4.98 compound 8 (A68) Inventive n.d. 220 320 −4.73 compound 9 (A67) Inventive n.d. n.d. 300 −5.12 compound 10 (A64) Inventive 134 300 227 −5.22 compound 11 (A13) Inventive 118 257 352 −5.1 compound 12 (A15)

[0297] A higher Tg and Tm may be beneficial and a higher TGA5% temperature (in other words lower volatility) may be advantageous for improved processing, in particular in mass production. Additionally, a LUMO level further away from vacuum level may be beneficial for performance of organic electronic devices.

[0298] Table 3 shows device data obtained for comparative compound 1 (comparative example 1 and 2) and inventive compounds 1 to 12 (examples 1 to 13).

TABLE-US-00004 TABLE 3 Performance of an organic electronic device comprising an organic semiconductor layer comprising a compound of formula (I) and comparative examples 1 and 2 Percentage of compound U(100- of formula Voltage at 1 h) at Compound of (I) in HIL 10 mA/cm.sup.2 30 mA/cm.sup.2 formula (I) [wt.-%] [V] [V] Comparative Comparative 6 3.85 0.67 example 1 compound 1 Comparative Comparative 10 3.83 0.27 example 2 compound 1 Example 1 Inventive 3 3.78 0.12 compound 2 (A65) Example 2 Inventive 9 3.69 0.07 compound 3 (A61) Example 3 Inventive 8 3.70 0.14 compound 4 (A60) Example 4 Inventive 6 3.70 0.08 compound 5 (A59) Example 5 Inventive 6 3.73 0.05 compound 6 (A58) Example 6 Inventive 6 3.78 0.11 compound 7 (A66) Example 7 Inventive 5 3.83 0.23 compound 8 (A68) Example 8 Inventive 7 3.82 0.16 compound 8 (A68) Example 9 Inventive 10 3.78 0.08 compound 8 (A68) Example 10 Inventive 13 3.75 0.15 compound 9 (A67) Example 11 Inventive 17 3.74 0.09 compound 9 (A67) Example 12 Inventive 3 3.76 0.06 compound 10 (A64) Example 13 Inventive 4.5 3.73 0.04 compound 10 (A64)
As can be seen in Table 3, the operating voltage is reduced compared to comparative examples 1 and 1. Furthermore, the voltage rise over time U(100-1 h) is substantially improved compared to comparative examples 1 and 2.
A lower operating voltage may be beneficial for improved battery life, in particular in mobile devices.

[0299] A lower voltage rise over time U(100-1 h) may be beneficial for improved stability over time of organic electronic devices.

[0300] The particular combinations of elements and features in the above detailed embodiments are exemplary only; the interchanging and substitution of these teachings with other teachings in this and the patents/applications incorporated by reference are also expressly contemplated. As those skilled in the art will recognize, variations, modifications, and other implementations of what is described herein can occur to those of ordinary skill in the art without departing from the spirit and the scope of the invention as claimed. Accordingly, the foregoing description is by way of example only and is not intended as limiting. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage. The invention's scope is defined in the following claims and the equivalents thereto. Furthermore, reference signs used in the description and claims do not limit the scope of the invention as claimed.