Topic：Fully printed organic tandem solar cells and modules: from concepts to demonstration
Time：2014.11.26 am 10:30-12:00
The tandem concept, in which two or more single cells with complementary absorption are stacked together and connected either in series or in parallel, is one of the most promising approaches to harvest photons at the highest possible potential. This concept can be successfully adapted for organic photovoltaics to simultaneously address the main loss-mechanisms in terms ofnarrow absorption windows and thermalization losses. The solution-processed lab-scale organic tandem solar cells developed rapidly over the past few years andthe power conversion efficiencies (PCEs) of >10% have been reported for both polymer and molecular tandem solar cells. According to several independently reported predictions, the tandem solar cells have the technical potential to exceed 20%PCE exhibiting an improvement by ~40% compared to the optimized single cells.
Ultra-fast laser processing was recently proven to yield solar modules with outstanding high fill factorsand fully additive open circuit voltages. Owning to the precise control over the ablation in micrometer range, organic modules fabricated by laser patterning are expected to reach a high geometrical fill factor of >95 %, indicating that organic modules are able to show comparable efficiencies to the corresponding solar cells. Moreover, the velocity of the laser-based module processing reaches ~1 ms-1, which fully satisfies the requirements for roll-to-roll production.
In this contribution, the tandem concept is combined with the ultra-fast laser patterning to generateefficient organic tandem modules on glass and flexible substrates. The design and development of fully printed organic tandem solar cells and modules are discussed in detail.