Solid-state Dye-sensitized Solar Cells Based On Chlorophyll As Hole Transport Material

Energy scarcity and environmental problems caused by the excessive use of fossil fuels are now increasingly becoming one of the most important constraints on human technological development.The seek for new sustainable and environmentally friendly energy sources has become an urgent issue.Solar energy is undoubtedly one of the most promising options.Since 1991,when firstly entered the field of vision of scientific researchers,dye-sensitized solar cells with high efficiency and low preparation cost have developed rapidly.However,the liquid redox medium in conventional liquid dye-sensitized solar cells suffers from high corrosiveness,volatility and leakage.Therefore,it is considered more effective to construct solid-state dye-sensitized solar cells by introducing an efficient and environmentally friendly hole transport layer.In solid-state dye-sensitized solar cells,the absorption of light depends mainly on the dye sensitizers.However,the most commonly used hole transport materials lack the ability to absorb light and therefore cannot work in synergy with the sensitizers to enhance the overall device light absorption.Chlorophyll,with its outstanding light harvesting capacity,is a naturally abundant pigment that achieves efficient charge separation and transfer by efficient light harvesting in photosynthesis.Additionally,chlorophyll has the advantage of a simple structure that is easy to regulate.Furthermore,specific derivatives of chlorophyll exhibit even more exceptional light harvesting and charge extraction abilities.Thus,using chlorophyll as a hole transport material in solid-state dye-sensitized solar cells is advantageous in further improving the cells’photoelectric performance.In this context,this paper investigates the effects of different dyes on the photovoltaic performance of solid-state dye-sensitized solar cells using molecularly engineered synthetic zinc-containing chlorophyll derivatives as the hole transport layer and develops photovoltaic devices with excellent photovoltaic performance.Firstly,using chlorophyll-a（Chl-a）as raw material,the synthetic porphyrin ring contains hydroxyl group at the C3 position,carbonyl group at the C13 position,and a zinc-containing chlorophyll derivative（Zn Chl）,which has a high carrier mobility and can realizeπ-πstacked J aggregates by a spin-coating process.The working mechanism and photoelectric performance of photovoltaic devices with Zn Chl as hole transport material and different indole dye molecules（D131,D149,D102）as sensitizers were explored.Among them,the device prepared with D131 indole dye as a sensitizer obtained the best power conversion efficiency of 1.18%,and the photoelectric performance was better than that of devices based on D149 and D102dyes.Therefore,chlorophyll derivatives as low-cost and environmentally friendly green materials provide a new strategy for applying them as hole transport materials,in solid-state dye-sensitized solar cells.To improve the performance of solid-state dye-sensitized solar cells containing zinc chlorophyll derivatives as the hole transport layer,we use a strategy of co-sensitizing photoanodes with a variety of sensitizers to improve the power conversion efficiency of batteries.The chlorophyll-a（Chl-a）derivative H₂Chl-1 was selected as the primary chromophore,and the chlorophyll-b（Chl-b）derivatives H₂Chl-2 and carotenoids（Car）were selected as compensating sensitizers for H₂Chl-1.Compared with Ti O₂-（H₂Chl-1）devices without Car co-sensitization,the power conversion efficiency of the devices prepared by H₂Chl-1 and Car as co-sensitizers increased by40%,the light absorption and electron injection efficiency of the photovoltaic devices were improved,and the charge transfer resistance at the interface was reduced.The above exploration based on chlorophyll derivatives as hole transport materials meets the needs of today’s green economy development,which makes us more deeply understand the great potential of natural pigments in photovoltaic devices,and is more conducive to the practical application of renewable clean energy.