The appropriate combination of semiconducting polymer–inorganic nanocomposites can enhance the existing performance of polymers-only-based photovoltaic devices. Hence, polyaniline (PANI)/zinc oxide (ZnO) nanocomposites were prepared by combining ZnO nanoparticles with PANI in four distinct ratios to optimize their photovoltaic performance. Using a simple coating method, PANI, ZnO, and its nanocomposite, with varying weight percent (wt%) concentrations of ZnO nanoparticles, i.e., (1 wt%, 2 wt%, 3 wt%, and 4 wt%), were fabricated and utilized as an active layer to evaluate the potential for the high-power conversion efficiency of various concentrations, respectively. PANI/ZnO nanocomposites are characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), atomic force microscopy (AFM), Fourier transform infrared (FTIR) spectroscopy, ultraviolet-visible (UV-vis) absorption, energy dispersive X-ray (EDX), and I-V measurement techniques. The XRD analysis showed a distinct, narrow peak, which corresponds to the wurtzite ZnO (101) plane. The SEM analysis verified the production of the PANI/ZnO composite by demonstrating that the crystalline ZnO was integrated into the PANI matrix. The elemental composition was determined by energy dispersive X-ray analysis (EDX), which confirmed the existence of PANI and ZnO without any impurities, respectively. Using Fourier transform infrared (FTIR) spectroscopy, various chemical bonds and stretching vibrations were analyzed and assigned to different peaks. The bandgap narrowing with an increasing PANI/ZnO composition led to exceptional optical improvement. The I-V characterization was utilized to investigate the impact of the nanocomposite on the electrical properties of the PANI/ZnO, and various concentrations of ZnO (1 wt%, 2 wt%, 3 wt%, and 4 wt%) in the PANI matrix were analyzed under both light and dark conditions at an STC of 1.5 AM globally. A high PCE of 4.48% was achieved for the PANI/ZnO (3 wt%), which revealed that the conductivity of the PANI/ZnO nanocomposite thin films improved with the increasing nanocomposite concentration.

This paper reports on the fabrication and photovoltaic characteristics of a heterojunction solar cell based on an organic small molecular semiconductor, N-749 black dye (N749-BD). To investigate the photovoltaic characteristics of N749-BD, an ITO/PEDOT:PSS/N749-BD/Ag device is prepared by spin casting a 100 ± 5-nm thin film of N749-BD on the poly(3,4, ethylene dioxythiophene):polystyrene sulfonate (PEDOT:PSS) film, which acts as buffer/hole transport layer (HTL) and indium tin oxide (ITO) is employed as a transparent conducting substrate. Under standard testing conditions (STC), i.e., 25 °C, 1.5 AM global and 100 mW/cm² irradiation, the photovoltaic parameters of the device, such as fill factor (FF) and power conversion efficiency (PCE), are found to be 0.65 and 3.8% ± 0.5%, respectively. Current-voltage (I–V) characteristics of the device are also studied in dark conditions to measure reverse saturation current (I₀), series resistance at the interface, rectification ratio (RR), barrier height (ϕ_b) and ideality factor (n). Optical bandgaps (E_g) of N749-BD thin film are found by applying Tauc’s plot on its ultraviolet-visible (UV-Vis) spectrum, which are measured to be 1.68, 2.67, 3.52 and 4.16 eV. External quantum efficiency (EQE) measurements of the fabricated device are studied, which demonstrate large value of EQE$\approx$12.89%, with peak intensity at 626 nm. Bond dynamics and compositional analysis of N749-BD is carried out via Fourier transformed infrared (FTIR) spectroscopy. Morphology of the thin film of N749-BD on quartz glass are investigated via scanning electron microscopy (SEM) with in-situ energy dispersive X-ray (EDX) spectroscopy which exhibits random distribution of N749-BD grains across the surface with nearly uniform grain sizes and shapes. The larger values of FF, PCE and EQE of ITO/PEDOT:PSS/N749-BD/Ag device suggests the potential of N749-BD to be utilized in low cost, simple manufacturing process and high performance of solar cells.

This work reports on the synthesis of small molecular semiconductor 2-(1H-pyrrol-1-yl)-anthracene-9,10-dione (PAD) via wet chemical precipitation route method for its possible potential applications in sensors. Thin film characterization of the synthesized PAD is carried out by studying its surface morphology, bond dynamics, and optical properties. For studying sensing characteristics of the PAD, its 100 nm thick film is thermally deposited on pre-patterned silver (Ag) electrodes over glass substrate having ~45 µm inter-electrode gaps to prepare Ag/PAD/Ag sensor. The effects of humidity (%RH), temperature (T), and illumination of light (E_v) on the fabricated Ag/PAD/Ag sensor are studied by changing one of the three (%RH, T, and E_v) parameters at a time and measuring the corresponding variations in capacitance (C) and capacitive reactance (X) of the device. As C and X also depend on frequency, sensing properties of the Ag/PAD/Ag sensor are measured at two different frequencies (120 Hz and 1 kHz) to find the optimum sensitivity conditions. To investigate reproducibility and repeatability of Ag/PAD/Ag sensor, each measurement is taken several times and also hysteresis loops of %RH vs. C are plotted at 120 Hz and 1 kHz to find the percent errors in each cycle of measurements. The sensor is active to sense humidity, temperature, and illumination within a broad range, i.e., from 15–93%RH, 293–382 K, and 1500–20,000 lx, respectively. Other key parameters of the sensor i.e., the humidity response time (T_Res) and recovery time (T_Rec), are measured, which are 5 and 7 s, respectively, whereas for light sensing the values of T_Res and T_Rec are measured to be 3.8 and 2.6 s, respectively. The measured values of T_Res and T_Rec for the fabricated Ag/PAD/Ag sensor are shorter and better as compared to those of previously reported for similar kind of small molecular based sensors. The sensing properties of Ag/PAD/Ag device exhibit the potential of PAD for humidity, temperature, and light sensing applications.