Plasmonic enhancement of betanin-lawsone co-sensitized solar cells via tailored bimodal size distribution of silver nanoparticles

Abstract

natural pigment-based photosensitizers are an attractive pathway for realizing low cost and environmentally friendly solar cells. Here, broadband light-harvesting is achieved using two natural pigments, betanin and lawsone, absorbing in the green and blue region of the solar spectrum respectively. the use of bimodal size distribution of Agnps tailored for each of the pigments to further increase their efficiency is the key feature of this work. This study demonstrates a significant enhancement in current-density, voltage, and efficiency by 20.1%, 5.5%, and 28.6% respectively, in a betanin-lawsone co-sensitized solar cell, via plasmonic enhancement using silver nanoparticles (Agnps). the optimum sizes of the nanoparticles have been calculated by studying their optical response and electric field profiles using Finite Difference Time Domain (FDTD) simulations, aimed at matching their resonant wavelengths with the absorption bands of the dyes. Simulations show that AgNPs of diameters 20 nm and 60 nm are optimum for enhanced absorption by lawsone and betanin respectively. The FDTD simulations of the plasmonic photoelectrodes demonstrated 30% and 15% enhancement in the power absorption by betanin and lawsone at the LSPR peaks of the 60 nm and 20 nm AgNPs respectively. An optimum overall concentration of 2% (v/v) and a ratio of 4:1 (20 nm:60 nm) of the bimodal distribution of the AgNPs, was determined for incorporation in the photoanodes. An average efficiency of 1.02 ± 0.006% was achieved by the betanin-lawsone co-sensitized solar cell with the bimodal distribution of AgNPs, compared to 0.793 ± 0.006% achieved by the non-plasmonic solar cell of otherwise identical configuration. Electrochemical impedance spectroscopy confirmed that the incorporation of the bimodal distribution of Agnps in the solar cells also enabled enhanced electron lifetime and reduced recombination compared to the non-plasmonic counterpart, thereby improving the charge transfer. the plasmonic enhancement methodology presented here can be applied to further improve the efficiency of other natural dye-sensitized solar cells. Since the seminal work in 1991 by O'Regan and Gratzel on Dye-Sensitized Solar Cells (DSSCs) 1 , immense interest has been directed towards their development in the last two decades. Owing to their inexpensive and facile processing requirements, DSSCs are becoming increasingly popular as an emerging photovoltaic technology 2-4. State-of-the-art DSSCs, which have achieved maximum efficiencies of 11.9% 5 , widely use metal-based dyes as the photosensitizer. Although these dyes are highly efficient sensitizers that effectively capture the entire visible spectrum, they employ rare metals such as ruthenium or osmium which require elaborate synthetic procedures. Moreover, they are expensive and toxic to the environment, making their disposal a problem. Therefore, natural pigments derived from plant sources, which are environment-friendly and inexpensive 6,7 , have come to the forefront as alternative photosensitizers. Several groups 8,...

The Recent Progress on Silver Nanoparticles: Synthesis and Electronic Applications

“…( b ) absorption spectra of the sensitized TiO 2 photoanodes, and ( c ) photocurrent density-voltage (J–V) curves of the assembled devices, copied with permission from Ref. [ 185 ], Nature, 2020.…”

High Performance Dye Sensitized Solar Cells by Plasmonic Enhancement of Silver Nanoparticles in ZnO Photoelectrode with Betanin Pigment

“…These results have prompted researchers to look for cheaper and more environmentally friendly alternative dyes. Natural pigments, including lawsome [2], chlorophyll [3,4] carotene [2,5,6], betanin [2,7], betalain [4,6,[8][9][10], anthocyanin [6,9,11,12,13,14] etc, are freely available in plant leaves, flowers, and fruits and have been used to fulfill the requirements of sensitizers. To date, average efficiencies achieved for natural DSSCs are ∼ 0.4%, with the highest being ∼ 1.5 -2.0% [2].…”

“…Natural pigments, including lawsome [2], chlorophyll [3,4] carotene [2,5,6], betanin [2,7], betalain [4,6,[8][9][10], anthocyanin [6,9,11,12,13,14] etc, are freely available in plant leaves, flowers, and fruits and have been used to fulfill the requirements of sensitizers. To date, average efficiencies achieved for natural DSSCs are ∼ 0.4%, with the highest being ∼ 1.5 -2.0% [2]. Most photoanodes that are used in DSSCs are made of semiconductor materials such as TiO 2 [2,11,15,16,17], SnO 2 [18], ZnO [1,19,20,21], Nb 2 O 5 , SrTiO 3 , Fe 2 O 3 , WO 3 and Ta 2 O 5 [20].…”

Betanidin isomerisation and decarboxylation, thermodynamic and charge transfer dye properties towards dye sensitised solar cells application

“…Hence, the way to increase it is of importance. Several studies aimed at improving the performance of natural dyes have been done by means of cosensitisation, [16][17][18][19][20] for example, via mixing of two natural dyes or synthetic dye and natural dyes; still, all these attempts lead to a slight shift of the efficiency.…”