TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Method: In the method (M1), the measuring step involves using a four-point probe or an eddy current probe. The step of growing the CNT forest involves putting the catalyst-incorporated substrate on a heater block in a chemical vapor deposition (CVD) chamber; heating the CVD chamber up to a temperature for the growth of CNT forest; holding the substrate in the CVD chamber at the temperature for the growth of CNT forest; providing a gas mixture consisting of CNT-forming precursors and carrier gases; and growing the CNT forest on the substrate such that the CNT forest are aligned in a direction perpendicular to the substrate. The hold temperature of the heater block in the CVD chamber is between room temperature and the temperature for the growth of CNT forest. The temperature for the growth of the CNT forest is 650-850 degrees C. The heating rate up to the temperature for the growth of CNT forest is 10-1000 degrees C/minute. The substrate that is heated up to the temperature for the growth of CNT forest stays less than 30 minutes in carrier gases. In the method before growing the CNT forest, carrier gases is supplied into the CVD chamber. In the method (M2), the CNT bundles in the CNT sheet or yarn is aligned in the same direction or cross each other perpendicularly. The hole conducting layer is a triple-layer in which the CNT sheets or yarns is laid between the hole conducting materials. In the method (M3), the CNTs are encapsulated by metal oxides by a process comprising coating a metal onto the CNTs; and oxidizing the metal using oxidants. Preferred Components: The catalyst film comprising iron, where the sheet resistance of the catalyst film is about 10 k Omega /square to 1 M Omega /square. The substrate comprises an oxidized material selected from silicon, metals, metal oxides and/or glass. The catalyst film comprises iron deposited on the substrate by a process selected from electron-beam evaporation, sputtering, and chemical vapor deposition. The bundle of CNTs comprises multi-walled CNTs. The CNT-forming precursor comprises acetylene, and the carrier gases comprise hydrogen and an inert gas. The inert gas is selected from helium, nitrogen, and argon. The flow rate of the acetylene is 200-1000 sccm; the flow rate of the hydrogen is 50-1000 sccm; and the flow rate of the inert gas is 1-30 slm. The CNTs of the bundle of CNTs comprises multi-walled CNTs that are entangled end to end, and the multi-walled CNTs are parallel to each other along the drawing direction. The hole conducting material comprises poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate), indium tin oxide (ITO) and p-type transparent metal oxides. The p-type transparent metal oxide has a work function of over 4.5 eV. The p-type transparent metal oxide is selected from iron oxide, nickel oxide, tin oxide, vanadium oxide and/or zinc oxide. In the method (M3), the metal oxide is a p-type transparent metal oxide with work function of over 4.5 eV. The p-type transparent metal oxide is selected from iron oxide, nickel oxide, tin oxide, vanadium oxide and zinc oxide. The metal oxide comprises a transition metal oxide. The metal oxide is coated onto the CNTs by a process selected from sputtering, electro-deposition and/or, chemical vapor deposition (CVD). The oxidants are selected from oxygen, ozone, hydrogen peroxide, and nitric acid. In the method (M4), the metal oxide comprises a transition metal oxide, where the transition metal oxide is selected from manganese oxide, nickel oxide, cobalt oxide, and iron oxide. EXAMPLE - No suitable example given.