Using Dual Microresonant Cavity and Plasmonic Effects to Enhance the Photovoltaic Efficiency of Flexible Polymer Solar Cells.

Wenfei Shen,Jianguo Tang,Xiaolin Zhang,Fanchen Bu,Guoqing Zhao,Jungheum Yun

doi:10.3390/nano10050944

Wenfei Shen, Jianguo Tang + Show 4 more

Open Access

https://doi.org/10.3390/nano10050944

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Abstract

Fabricating polymer solar cells (PSCs) on flexible polymer substrates, instead of on hard glass, is attractive for implementing the advantage and uniqueness of the PSCs represented by mechanically rollable and light-weight natures. However, simultaneously achieving reliable robustness and high-power conversion efficiency (PCE) in such flexible PSCs is still technically challenging due to poor light harvesting of thin photoactive polymers. In this work, we report a facile, effective strategy for improving the light-harvesting performance of flexible PSCs without sacrificing rollability. Very high transparent (93.67% in 400–800 nm) and low sheet resistance (~10 Ω sq−1) ZnO/Ag(O)/ZnO electrodes were implemented as the flexible substrates. In systematically comparison with ZnO/Ag/ZnO electrodes, small amount of oxygen induced continuous metallic films with lower thickness, which resulted in higher transmittance and lower sheet resistance. To increase the light absorption of thin active layer (maintain the high rollability of active layer), a unique platform simultaneously utilizing both a transparent electrode configuration based on an ultrathin oxygen-doped Ag, Ag(O), and film and plasmonic Ag@SiO2 nanoparticles were designed for fully leveraging the advantages of duel microresonant cavity and plasmonic effects to enhance light absorbance in photoactive polymers. A combination of the ZnO/Ag(O)/ZnO electrode and Ag@SiO2 nanoparticles significantly increased the short-current density of PSCs to 17.98 mA cm−2 with enhancing the photoluminescence of PTB7-Th film. The flexible PSC using the optimized configuration provided an average PCE of 8.04% for flexible PSCs, which was increased by 36.27% compared to that of the PSC merely using a conventional transparent indium tin oxide electrode.

Highlights

Great progress in polymer solar cells (PSCs) has been achieved via state-of-the art fabrication techniques utilizing novel donor and acceptor materials [1,2,3]
Flexible PSCs utilizing the OMOs as their front electrodes exhibited highly improved power conversion efficiencies compared to that of PSCs utilizing indium tin oxide (ITO), while still lower than that of the same PSCs fabricated on glasses coated with crystalline ITOs
Researchers generally agree that the plasmonic effect induced by LSPR and light scattering of metallic nanoparticles can be applied to photovoltaic devices to enhance the PCE performances [35,36]

Summary

Introduction

Great progress in polymer solar cells (PSCs) has been achieved via state-of-the art fabrication techniques utilizing novel donor and acceptor materials [1,2,3]. Researchers generally agree that the plasmonic effect induced by LSPR and light scattering of metallic nanoparticles can be applied to photovoltaic devices to enhance the PCE performances [35,36]. Jung et al fabricated a 3D microresonant cavity system by nanopatterning processes on PET substrate and reported an improved PCE that was increased by 26.4% owing to the enhanced light absorption and charge collection efficiency. Implementing the dual effects of plasmonic effect and microresonant cavity effects in flexible PSCs structures, light absorption may be greatly improved by the magnified electromagnetic field and enlarged light paths, and this will provide a way to enhance the photovoltaic performances of PSCs on flexible substrates. Improving light absorption was confirmed by clear evidences of the enhancement in the photoluminescence intensity of pure PTB7-Th film and PTB7-Th film with nanoparticles

Preparation of OMO Electrodes

Preparation of Polymer Solar Cell Devices

Characterizations

Simulation

Results and Discussion

Conclusions