66 Cheetah project WebSite: Today's Challenges
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OPV- Organic Photovoltaics

Organic solar cells (OPV) use carbon based materials, typically in forms of small molecules, dendrimers and polymers, to convert solar into electric energy. This enables the low cost production processing, such as printing and roll-to-roll solution coating, which are accompanied by very high throughput.

Additional advantages of OPVs are the light weight and flexibility of the technology. OPV is the only technology that enables entirely wet-coating and low temperature processing of full modules resulting in extremely low environmental footprint of the production process and therefore is the one with the highest promise for developing a truly disruptive PV technology.

OPVs have progressed significantly in the recent years not only for academic interest but also for the potential of affordable energy technology. State-of-the-art polymer solar cells are based on printing or coating of the electrodes, charge transport layers, and active layers on flexible substrates. Efficiencies over 11 % have already been reached via the development of new materials with tailored energy levels and solubility and improved device architectures. Additional improvements are coming from newly developed processes and technologies to create optimal micro- and nano-structures in the active layer.

This rapid progress suggests that the commercialization of OPVs is just around the corner. However, the field is still hampered by two challenges: the device stability and material economy. Today, the strategy for developing organic solar cells is based on improving power conversion efficiency and subsequently improving the stability through improved encapsulation methods and (often expensive) encapsulation materials. The concept of an encapsulationless solar cell offers on a contrary a rationale strategy for developing intrinsically stable solar cells based on the most stable materials and materials combinations apt for scaling up. Improving the intrinsic stability of the device can greatly aid both in the process of improving OPV lifetimes and in reduction of the production costs by relieving the requirements for the encapsulation materials.

 The initial objective of the OPV RTD activities is to develop an encapsulation less organic solar cell with both reasonable power output and stability. The generated results will then be used as a ground for developing encapsulated long-lived organic solar cells. Simultaneously, the project will focus on building methodology to systematically screen materials and layer stacks for enhanced stability and creating stability metrics for different materials.

(Published  by Suren GEVORGYAN, DTU)