Limits...
Photovoltaic properties of PSi impregnated with eumelanin.

Mula G, Manca L, Setzu S, Pezzella A - Nanoscale Res Lett (2012)

Bottom Line: A bulk heterojunction of porous silicon and eumelanin, where the columnar pores of porous silicon are filled with eumelanin, is proposed as a new organic-inorganic hybrid material for photovoltaic applications.The addition of eumelanin, whose absorption in the near infrared region is significantly higher than porous silicon, should greatly enhance the light absorption capabilities of the empty porous silicon matrix, which are very low in the low energy side of the visible spectral range (from about 600 nm downwards).The experimental results show that indeed the photocarrier collection efficiency at longer wavelengths in eumelanin-impregnated samples is clearly higher with respect to empty porous silicon matrices.

View Article: PubMed Central - HTML - PubMed

Affiliation: Dipartimento di Fisica, Cittadella Universitaria di Monserrato, Università degli Studi di Cagliari, S,P, 8 km 0,7, Monserrato (Ca), 09042, Italy. guido.mula@unica.it.

ABSTRACT
A bulk heterojunction of porous silicon and eumelanin, where the columnar pores of porous silicon are filled with eumelanin, is proposed as a new organic-inorganic hybrid material for photovoltaic applications. The addition of eumelanin, whose absorption in the near infrared region is significantly higher than porous silicon, should greatly enhance the light absorption capabilities of the empty porous silicon matrix, which are very low in the low energy side of the visible spectral range (from about 600 nm downwards). The experimental results show that indeed the photocarrier collection efficiency at longer wavelengths in eumelanin-impregnated samples is clearly higher with respect to empty porous silicon matrices.

No MeSH data available.


Interference peak ordinal vs. the inverse of the peak wavelength obtained from the data of Figure4. Blue triangles refer to the empty PSi layer and red circles to the eumelanin-impregnated PSi layer. The linear fits of the experimental data are also shown for the lower (right) and higher (left) energy sides of the explored spectral range.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3420258&req=5

Figure 5: Interference peak ordinal vs. the inverse of the peak wavelength obtained from the data of Figure4. Blue triangles refer to the empty PSi layer and red circles to the eumelanin-impregnated PSi layer. The linear fits of the experimental data are also shown for the lower (right) and higher (left) energy sides of the explored spectral range.

Mentions: In Figure 5 we show the dependence of the interference peak maxima number on the inverse of the wavelength for the two samples of Figure 4, the color code being also the same. If the refractive index had been constant, this plot would have been a straight line [45]. In our case, however, considering the large spectral range explored, the refractive index is not constant. For this reason, the curves have been fitted separately for the higher (left) and lower (right) energy sides of the spectra. Since the slopes of the linear fits related to the impregnated sample are always higher than those related to the empty sample, the results of Figure 4 demonstrate that the refractive index of the impregnated PSi layer is higher than that of the empty PSi layer in the whole spectral range examined. From the results of Figures 4 and 5, we can then conclude that the eumelanin impregnation process leads to an increase of both the absorption coefficient and the refractive index of the PSi matrix. Moreover, the absence of beats in the interference fringes of the impregnated layer indicates that the impregnation process is quite homogeneous throughout the whole PSi thickness and that there is no double layer given by a partial, depth-limited, eumelanin pore penetration.


Photovoltaic properties of PSi impregnated with eumelanin.

Mula G, Manca L, Setzu S, Pezzella A - Nanoscale Res Lett (2012)

Interference peak ordinal vs. the inverse of the peak wavelength obtained from the data of Figure4. Blue triangles refer to the empty PSi layer and red circles to the eumelanin-impregnated PSi layer. The linear fits of the experimental data are also shown for the lower (right) and higher (left) energy sides of the explored spectral range.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3420258&req=5

Figure 5: Interference peak ordinal vs. the inverse of the peak wavelength obtained from the data of Figure4. Blue triangles refer to the empty PSi layer and red circles to the eumelanin-impregnated PSi layer. The linear fits of the experimental data are also shown for the lower (right) and higher (left) energy sides of the explored spectral range.
Mentions: In Figure 5 we show the dependence of the interference peak maxima number on the inverse of the wavelength for the two samples of Figure 4, the color code being also the same. If the refractive index had been constant, this plot would have been a straight line [45]. In our case, however, considering the large spectral range explored, the refractive index is not constant. For this reason, the curves have been fitted separately for the higher (left) and lower (right) energy sides of the spectra. Since the slopes of the linear fits related to the impregnated sample are always higher than those related to the empty sample, the results of Figure 4 demonstrate that the refractive index of the impregnated PSi layer is higher than that of the empty PSi layer in the whole spectral range examined. From the results of Figures 4 and 5, we can then conclude that the eumelanin impregnation process leads to an increase of both the absorption coefficient and the refractive index of the PSi matrix. Moreover, the absence of beats in the interference fringes of the impregnated layer indicates that the impregnation process is quite homogeneous throughout the whole PSi thickness and that there is no double layer given by a partial, depth-limited, eumelanin pore penetration.

Bottom Line: A bulk heterojunction of porous silicon and eumelanin, where the columnar pores of porous silicon are filled with eumelanin, is proposed as a new organic-inorganic hybrid material for photovoltaic applications.The addition of eumelanin, whose absorption in the near infrared region is significantly higher than porous silicon, should greatly enhance the light absorption capabilities of the empty porous silicon matrix, which are very low in the low energy side of the visible spectral range (from about 600 nm downwards).The experimental results show that indeed the photocarrier collection efficiency at longer wavelengths in eumelanin-impregnated samples is clearly higher with respect to empty porous silicon matrices.

View Article: PubMed Central - HTML - PubMed

Affiliation: Dipartimento di Fisica, Cittadella Universitaria di Monserrato, Università degli Studi di Cagliari, S,P, 8 km 0,7, Monserrato (Ca), 09042, Italy. guido.mula@unica.it.

ABSTRACT
A bulk heterojunction of porous silicon and eumelanin, where the columnar pores of porous silicon are filled with eumelanin, is proposed as a new organic-inorganic hybrid material for photovoltaic applications. The addition of eumelanin, whose absorption in the near infrared region is significantly higher than porous silicon, should greatly enhance the light absorption capabilities of the empty porous silicon matrix, which are very low in the low energy side of the visible spectral range (from about 600 nm downwards). The experimental results show that indeed the photocarrier collection efficiency at longer wavelengths in eumelanin-impregnated samples is clearly higher with respect to empty porous silicon matrices.

No MeSH data available.