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We report the effect of a nanobump assembly (NBA) constructed with molybdenum oxide (MoO3) covering Ag nanoparticles (NPs) under the active layer on the efficiency of plasmonic polymer solar cells. Here, the NPs with precisely controlled concentration and size have been generated by an atmospheric evaporation/condensation method and a differential mobility classification and then deposited on an indium tin oxide electrode via room temperature aerosol method. NBA structure is made by enclosing NPs with MoO3 layer via vacuum thermal evaporation to isolate the undulated active layer formed onto the underlying protruded NBA. Simulated scattering cross sections of the NBA structure reveal higher intensities with a strong forward scattering effect than those from the flat buffer cases. Experimental results of the device containing the NBA show 24% enhancement in short-circuit current density and 18% in power conversion efficiency compared to the device with the flat MoO3 without the NPs. The observed improvements are attributed to the enhanced light scattering and multireflection effects arising from the NBA structure combined with the undulated active layer in the visible and near-infrared regions. Moreover, we demonstrate that the NBA adopted devices show better performance with longer exciton lifetime and higher light absorption in comparison with the devices with Ag NPs incorporated flat poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). Thus, the suggested approach provides a reliable and efficient light harvesting in a broad range of wavelength, which consequently enhances the performance of various organic solar cells.

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We demonstrate solution-processed Ga-doped ZnO incorporated as an interfacial electron transport layer into inverted organic solar cells with active layers comprising either PCDTBT or PTB7 mixed with PC 71 BM. The 5.03 at% Ga-doped ZnO showed the best efficiencies of 5.56% and 7.34% for PCDTBT and PTB7 polymers respectively.

We demonstrate the modular fabrication of nanocrystal/polymer hybrid bulk heterojunction solar cells based on breakwater-like CdSe tetrapod (TP) nanocrystal networks infused with poly(3-hexylthiophene) (P3HT). This fabrication method consists of sequential steps for forming the hybrid active layers: the assembly of a breakwater-like CdSe TP network followed by nanocrystal surface modification and the infusion of semiconducting polymers. Such a modular approach enables the independent control of the nanoscopic morphology and surface chemistry of the nanocrystals, which are generally known to exhibit complex correlations, in a reproducible manner. Using these devices, the influence of the passivation ligands on solar cell characteristics could be clarified from temperature-dependent solar cell experiments. We found that a 2-fold increase in the short-circuit current with 1hexylamine ligands, compared with the value based on pyridine ligands, originates from the reduced depth of trap states, minimizing the trap-assisted bimolecular recombination process. Overall, the work presented herein provides a versatile approach to fabricating nanocrystal/polymer hybrid solar cells and systematically analyzing the complex nature of these devices.

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A new approach is presented to control the nanomorphology of organic solar cells in a predictable, controllable, and easily‐scalable way. The nanoimprint lithography (NIL) is combined with a subsequent molecular diffusion step controlled by thermal annealing. The new approach is realized by using nanointerdigitated donor–acceptor structure, consisting of poly(3‐hexylthiophene‐2,5‐diyl) nanopillar arrays surrounded by phenyl‐C61‐butyric acid methyl ester. Subsequent thermal annealing leads to vertically aligned ordered quasi‐bulk heterojunctions with hierarchical nanostructure. The changes are studied in nanostructural and electrical properties of the pillar samples using scanning probe microscopy. In addition, grazing‐incidence small and wide angle X‐ray scattering yield detailed quantitative information on the molecular‐ to domain‐scale nanostructures. The changes in crystal size, chain orientation, and domain composition as a function of thermal anneal temperature and time are obtained. In addition, the conductive scanning force microscopy in quantitative imaging mode, applied to the pillar‐based samples for the first time, allows us to establish a clear relationship between nanomorphology, nanoelectrical property, and macroscale device performance. It is believed that the NIL combined with controlled molecular diffusion is a powerful method, which could be easily extended to other materials and processes to realize a whole variety of other hierarchical nanomorphologies.

High efficiency inverted organic solar cells are fabricated using the PTB7:PC71BM polymer by incorporating Zn-doped TiO2 (ZTO) and 0.05 wt% PEO:ZTO as interfacial electron transport layers. The 0.05 wt% PEO-modified ZTO device shows a significantly increased power conversion efficiency (PCE) of 8.10%, compared to that of the ZTO (7.67%) device.