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Improvement in the device performance of hydrogenated amorphous silicon (a-Si:H) thin-film solar cells (TFSCs) without hazardous doping gases and complex processes has been a long-standing aim for many researchers. In this work, we replaced the n -type Si layer in an a-Si:H TFSC with an interfacial dipole layer of conjugated polymer electrolyte material, poly [(9,9-bis(3′-( N , N -dimethylamino) propyl)-2,7-fluorene)- alt -2,7-(9,9-dioctylfluorene) (PFN), while keeping the conventional layer scheme. The addition of PFN eliminated the process complexity, improved the device performance, and generated a built-in potential ( V bi ) across the p -type Si layer. The power conversion efficiency of the optimized device reached a maximum of 7.17%, which is significant when using a toxicant-free layer. The open-circuit voltage was improved to 0.80 V from 0.47 V in comparison to a reference a-Si:H TFSC without PFN, and the stability in light and dark conditions were greatly enhanced. The fill factor was increased from 0.45 to 0.59 because of the enhancement in shunt/series resistance. The improvement in device performance is mainly due to the creation of an interfacial dipole by the PFN layer, which generated the V bi across the p -type Si layer, decreased the potential barrier between the i-Si layer and aluminum cathode, and consequently reduced the defects resulting from the coating of the i-Si layer and enhanced electron extraction. [ABSTRACT FROM AUTHOR]

The effects of epitaxial materials and solar cell design on the performance of solar cells grown by the multilayer approach are investigated. The novel solar cell structure with a p‐on‐n type configuration suggested exhibits improved uniformity in the photovoltaic performance because of the suppression of Zn diffusion. This approach provides routes to achieve further improvements and acts as a guideline for the commercialization of the multilayer technique. [ABSTRACT FROM AUTHOR]

Abstract The high stability and strong coupling nature of gold nanoparticles (Au-NPs) than other metal counter parts have attracted the solar cell industry to pursue enhanced performances. Herein, we report on the improved performance of polymer bulk hetero-junction (BHJ) solar cells by the incorporation of large-size Au-NPs in the hole transport layer of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS). To examine the reproducibility of the enhancement parameters, two different donor photoactive materials have been adapted and the role of larger-size (>70 nm, i.e. 71, 80, 87, 103 nm) Au-NPs in BHJ solar cells have been studied extensively. Significantly, when employing Au-NPs smaller than 80 nm, near-field coupling (localized surface plasmon resonance; LSPR) was prevalent, while the infusion of Au-NPs with sizes greater than 87 nm resulted in far-field scattering enhancement as the dominant effect, which was clearly determined using time resolved photo luminescence studies. The superior power conversion efficiency of 5.35% and 8.58% was achieved with PBDTTT-C: PC 61 BM and PTB7: PC 71 BM BHJs respectively, by employing 87 nm Au-NPs due to the balanced contribution of near- and far-field plasmonic effects, improved vertical coverage and better interfacial properties. This study illustrates that 87 nm Au-NPs is the maximum size to attain the improved efficiency, above which the rate of enhancement reduces dramatically. Graphical abstract Image 1 Highlights • Plasmonic enhancement in organic solar cells by gold nanoparticles (Au-NPs). • Au-NPs with 71 and 80 nm shows dominant near-field enhancement. • Au-NPs with 87 and 103 nm shows dominant far-field scattering enhancement. • Improved vertical coverage and work function also reason for improved performances. • 87 nm Au-NPs demonstrated the optimum condition of near- and far-field enhancements. [ABSTRACT FROM AUTHOR]

The effects of the gold nanoparticles (Au NPs) on performance of organic solar cells (OSCs) are systematically investigated based on blend of the low band gap polymer and fullerene. The localized surface plasmon resonance (LSPR) induced by the Au NPs enhance the light absorption in the active layer and the photoluminescence spectra showed a significant enhancement in their intensity which mainly contribute to increased light absorption of active layer induced by LSPR. The impedance spectroscopy study revealed that the introduction of Au NPs as interfacial layer decreases the sheet and charge-transport resistance between ITO/PEDOT:PSS or PEDOT:PSS/active layer. From the results, the introduction of Au NPs increased the rate of exciton generation and the probability of exciton dissociation, thus enhancing the short-circuit current density and the fill factor The optimized OSCs incorporated with Au NPs were found to have power conversion efficiency of 5.40% compared to control device (4.65%), measured by using an AM 1.5 G solar simulator at 100 mW/cm 2 light illumination intensity. [ABSTRACT FROM AUTHOR]

The effects of surface-treated graphene thin films on the performance of organic solar cells (OSCs) were systematically investigated for different surface treatments. Four different surface treatments were introduced for controlling the graphene work function and conductivity: annealing in argon ambient, dipping in acetone, ultraviolet irradiation, and nitrogen plasma treatment. The treated graphene films were utilized as interfacial layers between indium tin oxide electrodes and molybdenum oxide-based hole extraction layers in OSCs. The best performance was observed for the device that incorporated acetone-treated graphene, and was attributed to the increased short-circuit current due to the improved shunt and series resistance. [ABSTRACT FROM AUTHOR]