Comparative study of natural dye-sensitized solar cells using inedible extracts from kumkum, kamala and malabar spinach fruits

Abstract

In this work, natural dyes were extracted from inedible plant sources, especially seeds of Bixa orellana (kumkum), pericarp of Mallotus phillipensis (kamala) fruits and ripe fruits of Basella alba (malabar spinach) and a detailed comparative study on the efficiency of such extracts or natural compounds as dye sensitizers for solar cell performed. The major constituents or pigments in these extracts are bixin in Bixa orellana, rottlerin in Mallotus phillipensis and betalain/betacyanin in Basella alba fruits. The efficiency of the best performing devices was 0.67% for kumkum, 0.55% for kamala and 0.32% for malabar spinach extracts. Theoretical calculations were also performed to compare the results and it showed congruity with the experimental observations. The thermodynamic parameters such as the electron injection efficiency and the regeneration efficiency were calculated using density function theory (DFT) for the three natural dyes and it was observed that kumkum dye to be the most efficient and malabar spinach to be the least efficient among the three natural dye sensitizers as the same trend with the experimental results. These bio-compatible and inedible extracts are easily available and inexpensive for their use as sensitizers as an alternative to the toxic and expensive synthetic sensitizers.