{'fraction_non_alphanumeric': 0.025145371680025147, 'fraction_numerical': 0.019016187333019016, 'mean_word_length': 5.072519083969466, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 1, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Enhancement of Quantum Efficiency of A Dye-Sensitized Electrochemical Cell by using Triturated Zinc Oxide Mixed with Two Organic Dyes, Azure C and Rose Bengal

For efficiently utilising solar energy, when suitable nanoparticles are being engineered, triturated zinc oxide an eco-friendly, easily available, low-cost material has been used as an agent for solar energy conversion. Two organic dyes Azure C and Rose bengal having absorption bands in two different spectral regions at 545 nm and 610 nm respectively, were chosen in order to overcome the band absorption limits of each dye and utilise the broad spectrum of solar radiation. The material was mixed with these two dyes in a specially devised electrochemical cell and photovoltage with significant efficiency was generated. The energy conversion efficiency of the cell using three different potencies 6C, 30C and 200C of triturated zinc oxide with the same concentration of two dyes (0.5x10-5 M) in all cases are 0.39%, 0.43% and 0.35% respectively. The efficiency is only 0.15% for the mixed dye under similar conditions.


Introduction
Mankind faces a great energy challenge due to the depletion of fossil fuels at an alarming rate with exponential increase in population and growing demand for the modern lifestyle. To overcome this situation, utilisation of omnipresent and abundant solar energy has become the most promising one. Conventional silicon technology based photovoltaics has its own limitations. So research on developing new and novel materials for conversion of solar energy into electrical energy with high efficiency is emphasised. Many photosensitive dyes are being used for such conversion. [1][2] The invention of nanoparticles, which possess the unique chemical and physical properties with size and shape variations, has a strong impact in photovoltaic technology as they can facilitate the conversion process of solar energy to electrical energy. [3][4][5][6][7][8][9][10][11] International Journal of High Dilution Research 2017; 16(1): [1][2][3][4][5][6] Available online at www.highdilution.org For designing new and more effective light energy harvesting devices in cost effective way, several nanomaterials have been synthesised. Amongst them, TiO2, ZnO, SnO2 are the maximum utilised nanomaterials due to their proper physical and chemical properties. [12][13][14] While searching for novel and suitable materials, the idea of utilisation of the nanoparticle aspect of triturated zinc oxide (ZnO) has been explored. 15 This material is in the true sense a quite innovative one for use as an agent for solar energy conversion.
To ensure the performance of the electrochemical cell over a broad solar spectrum range, two dyes Azure C and Rose bengal, having absorption bands in two different spectral regions 545 nm and 610 nm respectively, were chosen in order to overcome the band absorption limits of each dye and were combined together.
Our result shows that photo-induced voltage with significant efficiency is generated when triturated ZnO is used in combination of these two different photosensitive organic dyes in a specially devised electrochemical cell. The energy conversion efficiency of the cell using three different potencies 6C, 30C and 200C of triturated zinc oxide with a same concentration of the two dyes (0.5x10 -5 M) in all cases are 0.39%, 0.43% and 0.35% respectively. The efficiency is only 0.15% for the mixed dye under similar conditions.  The two arms of the U-shaped glass cell were separated by a platinum foil barrier.

Result and discussion
The photovoltage generation in EC cell has been observed using Azure C and Rose bengal solution and triturated zinc oxide (Figure-II).  The I-V characteristic of the cell was studied (Figure-III) and the energy conversion efficiency has been calculated for all four cases (Table 1). In all cases, photo-induced voltage generation upon illumination started rising with time and reached a maximum saturation value and remained constant at that value. When the light was cut off the voltage decreased slowly and the storage duration for 30C was more than 4 hrs to reach the initial value. Also at this potency, In order to understand how triturated ZnO tuned the photoelectric properties of the dye molecules, the absorption spectra of the mixed dye in presence of triturated zinc oxide at different potencies had been studied (Figure-IV). Azure C and Rose bengal have their characteristic bands at 545 nm and 610 nm respectively. With the addition of the triturated ZnO, the characteristic peaks of the dye remain unchanged but absorbance increased. Our experimental results on photovoltage generation using triturated ZnO show presence of nanoparticles of almost spherical shape and particle sizes within 5-7 nm. 16 Due to adsorption of dye molecule on the surface of triturated ZnO nanoparticles, the absorption efficiency of the dye molecule increased. 17 There is also a high possibility of forming exciplex between these two dyes at excited state which could not participate in the process of conversion of solar energy. The addition of triturated zinc oxide also plays a vital role here. As the dyes got adsorbed on the surface of these nanoparticles they could participate now actively in the conversion process and the problem of spectral loss was reduced by better exploitation of the incident photon. The increase in efficiency of triturated zinc oxide at 30C to 6C can be explained by the fact that with increasing potency the particle size decreases, leading to increased surface to volume ratio. 18 However, at 200C the concentration of nanoparticle is very low to participate in conversion process resulting in lower efficiency than 6C and 30C.

Conclusion
Our study of photovoltage generation in a dye-sensitized photo-electrochemical cell using Azure C, Rose bengal and triturated zinc oxide at three different potencies shows that with addition of triturated zinc oxide in mixed solution of Azure C and Rose bengal system, magnitude of photovoltage, storage duration and energy conversion Spectral studies reveal that with the addition of the nanoparticle, the characteristics of the dye solution remains unchanged while the only overall optical density of the system increases indicating that there is no chemical reaction between the dyes and the triturated zinc oxide nanoparticle.