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We investigated flexible W-doped In2O3 (IWO) electrodes prepared by arc plasma ion plating (APIP) as a substitute for sputtered amorphous ITO electrodes in flexible perovskite solar cells (FPSCs). In spite of the room temperature ion plating process, the APIP-grown IWO film showed a low sheet resistance of 37.14 Ohm/square, a high optical transmittance of 96.0%, high near IR transmittance, and a small bending radius of 5 mm. In addition, the IWO film shows an atomically smooth surface with a root mean square roughness of 0.83 nm due to the absence of the resputtering effect during the ion plating process. The FPSC with the ion-plated IWO electrode showed comparable performances to a commercial amorphous ITO electrode in an FPSC with an open circuit voltage (0.837 V), short circuit current (18.67 mA/cm2), fill factor (72.54%), and power conversion efficiency (11.33%). Moreover, the microstructure and interfacial structure of the APIP-grown IWO film employed in a FPSC were examined by high-resolution transmission electron microscopy and the sheet resistance of the IWO films was correlated to the FPSC performance. [ABSTRACT FROM AUTHOR]

The authors investigated the effects of MoO3 doping power on the electrical, optical, and structural properties of MoO3-doped In2O3 (IMO) films for use as transparent electrodes in organic solar cells (OSCs). By optimizing the RF power of the MoO3 target (30 W), they obtained IMO films with sheet resistance of 24.57 Ω/sq and optical transmittance of 81.57%, comparable to conventional Sn-doped In2O3 (ITO) electrodes. In particular, the IMO film exhibited a high optical transmittance in the near-infrared (NIR) wavelength region due to the effects of Mo dopant with high Lewis acid strength and high mobility. In addition, strongly oriented (222) grains led to a smooth surface of the IMO electrode with root mean square roughness of 2.344 nm. The OSC fabricated on the optimized IMO electrode showed cell performances with a fill factor of 64.66%, a short circuit current of 8.058 mA/cm2, an open circuit voltage of 0.611 V, and a power conversion efficiency of 3.186%, which are nearly identical to OSCs with an ITO reference. This indicates that the IMO film is a promising alternative to the ITO electrode for the tandem OSC absorbing NIR wavelength region. [ABSTRACT FROM AUTHOR]

The authors report the characteristics of organic solar cells (OSCs) fabricated on HNO3-treated multilayer graphene (MLG) transparent electrodes. MLG transparent electrodes were prepared using chemical vapor deposition and a multitransfer process. Compared to untreated-MLG electrodes with a fairly high sheet resistance (274 ± 1 Ω/sq) even though three layers of graphene were stacked together, HNO3-treated MLG electrode shows a lower sheet resistance of 119 ± 1 Ω/sq. OSCs (MLG/poly (3,4-ethylenedioxythiophene):poly(styrenesulfonate)/Poly(3-hexylthiophere)/1-(3-methoxycarbonyl)-propyl-1-phenyl-(6,6)C61/Ca/Al) fabricated on untreated-MLG transparent electrodes had an open-circuit voltage of 0.575 V, a short-circuit current of 8.08 mA/cm2, a fill factor of 43.5%, and a power conversion efficiency (PCE) of 2.02%. In contrast, application of HNO3-treated MLG films as transparent electrodes for OSCs led to improved performance with an open-circuit voltage of 0.602 V, a short-circuit current of 8.26 mA/cm2, a fill factor of 57.5%, and a PCE of 2.86%. These results suggest that HNO3 treatment is a promising method for improving the performance of large-area OSCs based on MLG electrodes. [ABSTRACT FROM AUTHOR]

Enhanced performance of inverted polymer solar cells (PSCs) is demonstrated by indium tin oxide (ITO) interfacial tuning via a water-soluble polyfluorene (WPF-6-oxy-F). Kelvin probe studies and dark current-voltage curves demonstrated that the WPF-6-oxy-F layer reduces the ITO work-function because of the favorable interfacial dipole formed by the WPF-6-oxy-F interlayer, thereby enhancing the built-in potential and reducing the interface resistance. As a result, introduction of the WPF-6-oxy-F by simple solution processing into the inverted PSCs dramatically enhanced cell-performances. This approach could be very beneficial and an important step for the future development of all-solution-processed or roll-to-roll processed PSCs. [ABSTRACT FROM AUTHOR]

We demonstrate the fabrication of inverted-structure organic solar cells (OSCs) with graphene cathodes. The graphene film used in this work was work-function-engineered with an interfacial dipole layer to reduce the work function of graphene, which resulted in an increase in the built-in potential and enhancement of the charge extraction, thereby enhancing the overall device performance. Our demonstration of inverted-structure OSCs with work-function-engineering of graphene electrodes will foster the fabrication of more advanced structure OSCs with higher efficiency. [ABSTRACT FROM AUTHOR]

The use of periodic submicrometer structures as an efficient light-trapping scheme was investigated for high performance organic solar cells (OSCs) based on poly(3-hexylthiophene) and 1-(3-methoxycarbonyl)-propyl-1-phenyl-(6,6)C61. The gratings on an active layer are achieved by a soft lithographic approach using photoinduced surface-relief gratings (SRGs) on azo polymer films and poly(dimethylsiloxane) as a master and stamp, respectively. Incident photon to current conversion efficiency and the power conversion efficiency of OSC with gratings increased primarily due to enhanced short circuit current density, indicating that SRGs induce further photon absorption in active layers by increasing the optical path length and light trapping. [ABSTRACT FROM AUTHOR]

The authors report on a spray deposition method as a cost-efficient technique for the fabrication of organic solar cells (OSCs). Active layers of OSCs were fabricated using conventional handheld airbrushes. Although the spray deposited film showed a relatively rougher surface than spin coated ones, pinhole-free and constant thickness films could be obtained. An optimized OSC showed 2.83% of power conversion efficiency and 52% of incident photon to current conversion efficiency even though the device was fabricated in air. The performance of sprayed OSCs was comparable to that of the spin coated devices fabricated in air. [ABSTRACT FROM AUTHOR]

The use of a solution-processed gold chloride (AuCl3) as an anode interfacial modifier was investigated for high-performance polymer solar cells (PSCs). Kelvin probe, 4-point probe, and X-ray photoelectron spectroscopy studies demonstrated that AuCl3 increases the indium-tin-oxide (ITO) work-function and decreases the ITO sheet resistance, because of Au nanoparticle formation and Cl adsorption by the AuCl3 treatment to induce a p-doping effect, thereby improving the built-in potential and interface resistance. As a result, the introduction of AuCl3 by simple solution processing remarkably improved cell-performances, indicating that AuCl3 is an efficient anode interfacial modifier for enhancing PSC-performance. [ABSTRACT FROM AUTHOR]

We demonstrate that solution-processed carbon nanosheet (CNS) films can efficiently serve as transparent electrodes for organic solar cells (OSCs). The CNS was obtained by spin-coating of polyacrylonitrile (PAN) dissolved in dimethylformamide on quartz substrates, followed by stabilization and carbonization processes to convert polymer into CNS. The thickness of the newly developed CNS films was easily controlled by varying the PAN solution concentration. The polymer-converted CNS films were intensively examined for the feasibility of the use as transparent anodes in solar cells. This approach could be highly desirable for all-solution-processed or printed OSCs. [ABSTRACT FROM AUTHOR]