DS0202 - Captage des énergies renouvelables et récupération des énergies de l’environnement

Innovative Diffuse transparent Electrodes for solar cells applications – INDEED

Submission summary

INDEED proposes an original and innovative way to fabricate efficient transparent electrodes with varying haze factor values as well as their integration into solar cells, with the goals of using low-cost and abundant materials coupled with low cost deposition methods. The involved multidisciplinary consortium can tackle the tasks with complementary approaches dealing with the fabrication, characterization of physical properties of these thin Transparent Conductive Oxide (TCO) layers, modelling of the carrier transport and optical properties as well their integration into two types of promising solar cells: thin Si films (LPICM) and CIGS (IRDEP). A very high value of the haze (40-50%), coupled with excellent transparency and low sheet resistance, appears indeed very promising for enhancing solar cell performances. The presence of Lotus Synthesis Company within the consortium is also a clear asset in terms of precursor development and up-scaling of the diffusing Fluor-doped Tin Oxide (FTO).
Transparent electrodes are one of key components of the information technology (displays) and energy applications (photovoltaics, architecture and window glasses). The associated markets related to TCO have grown exponentially over the past decade due to the proliferation of large LCDs, thin film solar cells, OLEDS, or touch screens. Therefore, an intensive research has been devoted to this type of materials. Indium Tin Oxide is the main used TCO but it is of rare supply and indium-free solutions are therefore requested. TCO play a crucial role in solar cell technologies which is to collect photo-generated charges in the absorber, thus extracting current from the active region of the cell and allowing the generated carriers to be collected. At the same time, they must be transparent to incident light in the required spectral range to allow light into the cell to generate electron-hole pairs. This double function is usually accomplished by TCOs.
A key property is the haziness of TCOs, which is the ratio between diffused and total transmitted light intensities. A large haze factor is required for solar cell applications since it can increase the optical path length and then the photon absorption by the photo-active layer. This allows the use of thinner absorbing layers, which may lower recombination losses and therefore enhance the solar cell efficiency. The project INDEED is based on a very recent way proven to grow efficiently TCO (especially FTO) with varying haze factors on the one hand and on the expertise, competence and complementarity between the different teams of the consortium on the other hand. While INDEED will be focused on rigid substrates (glass), the flexibility can be reached since diffusive FTO can also be fabricated on polymeric substrates which exhibit improved mechanical resistance when compared with non-diffuse FTO layers. INDEED proposes innovative solutions in order to fabricate efficient transparent electrodes with varying haze factor values (up to very large values: 40-50%) as well as their integration into two types of solar cells, with the objectives of developing low cost methods and abundant materials for enhancing solar cell efficiency.
The results of electrical and optical characterization will be used to quantify, via optical modelling, the impact of the material properties on the power conversion efficiency. These electrodes will be tested in single junction PIN and tandem PIN/PIN Si devices fabricated at LPICM as well as CIGS solar cells at IRDEP. The choice of the two types of solar cells appears pertinent since the high efficiency and low cost are possible for both silicon thin film devices which have reached record efficiencies of 16.3% (for a triple junction) and CIGS solar cells which reach 21.7%. They exhibit a high potential development in the PV market and the French research community is foreseen to play an important role in their development.

Project coordination

Daniel BELLET (Laboratoire des Matériaux et du Génie Physique)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.


CNRS-IRDEP Institut de Recherche et Développement sur l'Energie Photovoltaïque (IRDEP)
LS Lotus Synthesis
LPICM-CNRS Laboratoire de Physique des Interfaces et Couches Minces (LPICM)
LMGP Laboratoire des Matériaux et du Génie Physique

Help of the ANR 370,769 euros
Beginning and duration of the scientific project: December 2015 - 36 Months

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