High-Lifetime Semi-Transparent Polymer Solar Cell for Building Applications( I )

Building photovoltaic has been considered as emerging green technology. For the high volume installation in building windows the solar cell has to meet several criteria including semitransparency, large-area, low-cost, light-weight, long lifetime, as well as low toxicity. Even though the efficiency is not the highest compared with other technologies, organic solar cell satisfies most of the criteria except for concern on lifetime and large-area fabrication. In the past our group has developed a world-leading blade-coating technology for large area solution fabrication of organic solar cell and light-emitting diodes. Recently we found that devices made of blade-coating can overcome the problem of short lifetime typically found in conventionally spin-coated devices. Under continuous operation the half-lifetime is over 8000 hours. This makes possible a real commercial building application. In addition, we have also successfully developed a n-doped, cross-linkable fullerene and applied it to tandem organic solar cells. Encouragingly, a power conversion over 10% has been demonstrated. This project aims to develop cost-effective, large-area semitransparent organic solar cells with high power conversion efficiency and good stability based on halogen-free process. To achieve this goal, we employ an integrated approach by combining the materials innovation (transparent electrode, cathode interfacial layer, and encapsulation layer) with advanced processing technique (blade coating and halogen-free solvent) and device engineering (tandem and microcavity structures). The resulting devices can be applied as multifunctional smart windows that can generate electricity while allowing smart-tuning of sunlight transmission. These results can demonstrate the practical applications of large-area organic solar cells in commercial products.