In this work, we propose poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) material to form a hybrid heterojunction with amorphous silicon-based materials for high charge carrier collection at the frontal interface of solar cells. The nanostructural characteristics of PEDOT:PSS layers were modified using post-treatment techniques via isopropyl alcohol (IPA). Atomic force microscopy (AFM), Fourier-transform infrared (FTIR), and Raman spectroscopy demonstrated conformational changes and nanostructural reorganization in the surface of the polymer in order to tailor hybrid interface to be used in the heterojunctions of inorganic solar cells. To prove this concept, hybrid polymer/amorphous silicon solar cells were fabricated. The hybrid PEDOT:PSS/buffer/a-Si:H heterojunction demonstrated high transmittance, reduction of electron diffusion, and enhancement of the internal electric field. Although the structure was a planar superstrate-type configuration and the PEDOT:PSS layer was exposed to glow discharge, the hybrid solar cell reached high efficiency compared to that in similar hybrid solar cells with substrate-type configuration and that in textured well-optimized amorphous silicon solar cells fabricated at low temperature. Thus, we demonstrate that PEDOT:PSS is fully tailored and compatible material with plasma processes and can be a substitute for inorganic p-type layers in inorganic solar cells and related devices with improvement of performance and simplification of fabrication process.

Thin-film hybrid organic-inorganic photovoltaic structures based on hydrogenated silicon (Si:H), poly(3,4ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) polymer Al-doped ZnO (AZO) films deposited on different types of flexible substrates have been fabricated and investigated. The compatibility of the polymer and inorganic materials regimes and deposition techniques used for device fabrication has been demonstrated on flexible substrates. Morphological characteristics of transparent Al-doped ZnO (AZO) films deposited on substrates have been measured by atomic force microscopy. Electronic characteristics of the fabricated photovoltaic structures have been measured and analyzed for different thicknesses of the transparent electrodes and different substrate types. Photovoltaic hybrid structure on polyethylene naphthalate (PEN) substrate showed the best characteristics: short circuit current density J_sc = 9.79 mA/cm², open circuit voltage U_oc = 565 mV, and PCE η = 1.3%. To analyze the mechanisms governing the device performance, short circuit current density spectral dependence of the devices fabricated on different types of flexible substrates has been measured. As demonstrated by our analysis, the structures on PEN substrates, besides better substrate transmittance, also show better junction properties.

Temperature dependence of DC conductivity σDC(T) of spin-coated poly (3,4 ethylenedioxythiophene): poly(4-styrenesulfonate) (PEDOT:PSS) films has been studied. σDC(T) was measured in films deposited from mixtures of PEDOT/PSS: H ₂ O (1:0.5), PEDOT:PSS (without dilution), PEDOT/PSS: Isopropyl Alcohol (IPA) (1:0.5) and PEDOT/PSS:IPA (1:1). Room temperature conductivity σ _RT of PEDOT/PSS films is enhanced from 4.46×10 ^-5 S/cm to 6.07×10 ^-4 S/cm after dilutions with H ₂ O and IPA (1:1), respectively. Experimental data is fitted with two different transport models: thermal activated conduction and variable range hopping (VRH) model. It is found that σ _DC (T) of PEDOT/PSS:IPA (1:1) sample can be described by the one-dimensional (1D) VRH model with an pre-exponential factor σ ₀ =28.5 S/cm and material-dependent parameter T ₀ =39,204 K.

Indium tin oxide (ITO) thin films were deposited by magnetron sputtering with different oxygen flows rates (%O2 = 1 % to 0 %). The films were deposited by RF discharge in argon/oxygen atmosphere with a RF power W = 150 W at substrate temperature T = 175° C and pressure P = 6 mTorrs. Photoelectric parameters of fabricated ITO films were characterized by four-point probe method and transmittance measurements. It was found that reducing oxygen concentration the sheet resistance decreases. For samples fabricated in oxygen atmosphere the transmittance reached values above 90 %. However, the sample with post-deposition thermal treatment at T = 300 °C in oxygen atmosphere shows the best transmittance (95 %) and lowest value of sheet resistance (Rs= 27 ohms-square). Finally, the transparent conducting oxides were applied in hybrid organic-inorganic photovoltaic structures. The best power conversion efficiency in AM-1 sunlight η = 2.13 % was obtained for a structure with ITO fabricated at oxygen concentration %O2 = 0.25 % in comparison with an efficiency η = 1.87 % obtained for a structure fabricated with commercial ITO.