No abstract

Various types of next-generation encapsulation films based on polyolefins have recently been introduced and could attract market attention. These material innovations can be classified as polyolefin elastomer (POE) and thermoplastic polyolefin (TPO) encapsulants, both of which consist of a polyethylene backbone with different side groups. The main advantage of these materials is the replacement of the vinyl acetate side groups of state-of-the-art encapsulant ethylene vinyl acetate (EVA) so that acetic acid cannot be formed. The main objective of this paper is to investigate the material properties of next-generation encapsulant films and compare them to an EVA reference. Two commercially available EVA alternatives (POE and TPO) have been selected. The material properties of single films as well as the electrical performance of test modules using these different encapsulants were investigated. The different films show comparable optical, thermal and thermo-mechanical properties, with slight differences in UV transparency and melting temperatures. Only shear viscosity values are higher for TPO than for POE and EVA, which requires adaption of the photovoltaic (PV) module lamination parameters. The test modules comprising the different encapsulation films show minor differences in the electrical performance after manufacturing; upon accelerated aging, no significant power loss is observed. But compared to TPO or POE, after 3000 h of damp heat exposure, test modules with EVA show the beginning of corrosion effects at the silver grid and above the ribbons. Based on the results, it can be stated that the new polyolefin encapsulation materials show great potential to be a valid replacement for EVA.

Highly efficient organic solar cells with all-solution-processed low-cost transparent front contacts based on highly conductive formulations of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) are reported, demonstrating the feasibility of replacing the costly conventional vacuum-deposited indium-tin-oxide contacts by means of simple printing techniques. For small cell areas, the relatively high sheet resistances were found to be less detrimental to the photovoltaic performance than the deficiencies in the transparency of the contact layer.

No abstract

No abstract