Implementation of submicrometric periodic surface structures toward improvement of organic-solar-cell performances

Abstract

Submicrometric periodic patterning of an organic solar cell surface is investigated in order to optimize the photovoltaic conversion efficiency of the device. Patterning is achieved using a single-step all-optical technique based on photoinduced mass transport in azopolymer films. The polymer film with a structured surface is used as a substrate for an organic solar cell based on a copper phthalocyanine/C60 heterojunction. The effect of periodic patterning is investigated through the solar-cell optical-absorption properties and external quantum efficiency measurements. The possibility to increase the short circuit current density and the corresponding photovoltaic conversion efficiency is evidenced with one-dimensional periodic structures.

Angle insensitive enhancement of organic solar cells using metallic gratings

“…These type of gratings are less studied than the square gratings, however we will show that the usage of these triangular gratings can give great absorption enhancement. Several lithographic methods (nanoimprint, optical or electron beam lithography) for metallic grating structures can be used to produce these types of gratings [16][17][18][19]. The chosen metal back contact material is silver, as it allows for low metal absorption losses, and beneficial SPP resonance wavelengths.…”

Effects of Nanoimprinted Structures on the Performance of Organic Solar Cells

“…Patterning active layers with gratings or wrinkle-like topography by soft lithography led to light trapping into the active films [17][18][19]. Other light trapping schemes based on the patterned electrodes were also reported using buried nanoelectrodes [20], microprism substrates [21], and azopolymer based submicrometer relief substrates [22][23][24]. Although the enhancements in light absorption have been demonstrated in those devices, the practical adoption of these light manipulation methods is hindered due to the difficulty of precisely engineering the multiple periodic nanostructures, the incompatibility with the thin organic films, the limited spectral response, and complicated fabrication procedures over large areas.…”

“…A few light trapping management techniques have been investigated for enhancing photon absorption and PCEs in OSCs [15][16][17][18][19][20][21][22][23][24]. Patterning active layers with gratings or wrinkle-like topography by soft lithography led to light trapping into the active films [17][18][19].…”

Les cellules photovoltaïques organiques

“…Il est donc indispensable de chercher à augmenter la valeur de α par ingénierie moléculaire, mais également d'augmenter la valeur de l en favorisant le couplage de la lumière dans les couches organiques. L'utilisation en face arrière d'une électrode qui possède une structure périodique [6], ou d'un réseau de Bragg [7], permet d'obtenir ce couplage recherché, comme le montre la figure 3. La lumière est alors guidée dans le film organique et la distance d'interaction photons-matière devient grande.…”