Controlling both the film crystallinity of the active layer for better charge transport and the interdiffusion between donor and acceptor materials for optimal bicontinuous networks is essential in producing pseudo-bilayer polymer solar cells. In this work, we investigated the influence of a doping solution-processable small molecule with high carrier mobility, 5,11-bis(triethylsilylethynyl) anthradithiophene (TES-ADT), on the performance of pseudo-bilayer polymer solar cells made of an underlayer of poly(3-hexylthiophene) (P3HT) and an upper layer of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). By analysis of the X-ray diffraction and UV−vis absorbance spectra of P3HT:TES-ADT blend films it was demonstrated that the film crystallinity was enhanced by TES-ADT doping in the P3HT underlayer. The hole mobility extracted from the current density−voltage curves of hole-only devices based on P3HT:TES-ADT demonstrated an optimized value with proper TES-ADT doping and thermal annealing. An intermixed photoactive layer was observed for the annealed device, indicating the occurrence of interdiffusion with a large interfacial area. With improved film crystallinity and interdiffusion, the optimal device performance was obtained when 5% TES-ADT was blended with P3HT and a thermal annealing treatment at 150 °C for 1 min was conducted. At that optimal condition, the mean crystallite size was increased by 35%, and hence the enhancement of 8% and 14% in power conversion efficiency and short-circuit current density was observed, respectively.

In this study, a wet chemical method of etching indium-tin-oxide (ITO) nanorods from commercially available ITO-coated glass is proposed and its applicability to polymer solar cells (PSCs) is validated. The ITO nanorods can be fabricated within a few minutes using the proposed method. The ITO-nanorodbased PSCs show 67% and 46% improvement in short-circuit current density and power conversion efficiency, respectively, compared with devices based on flat ITO electrodes. The enhanced performance is related to the anti-reflection and light-scattering properties of ITO nanorods, which enhance incident light intensity and light-trapping properties.

Indium-tin-oxide (ITO) nanorods were fabricated in 10 min from commercially available ITO substrate using wet chemical etching method. The optical properties of the ITO nanorods were investigated using transmission spectroscopy and dark-field optical microscopy. The transmittance and light-scattering characteristics of the ITO nanorods were better than those of ITO film. The ITO nanorod layer was further used as a transparent anode in polymer light-emitting diodes (PLEDs). The brightness and current efficiency of the PLED with the ITO nanorod layer were enhanced. This performance enhancement can be attributed to the excellent optical and electrical properties of the ITO nanorod layer.

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