Abstract
Although the efficiency of inorganic solar cells have been reached 24.7% and even 34% for tandem cells, it is not suitable for commercial application due to its high cost. Much more attention has been put to organic solar cells due to its simple and cost-effective fabrication process. Furthermore, flexible substrates and the potential to scale up to large area make it a promising alternative to silicon-based solar cell. In our study, cesium carbonate (Cs2CO3) and molybdenum oxide (MoO3) have been used as electron- and hole- transport layers. Besides, they also change work function of ITO and metal electrode by forming a thin dipole layer. A bulk heterojunction BHJ consisting blending of P3HT and PCBM in 1, 2-Dichlorobenzene spin-coated on ITO-coated glass is used as our active layer. For device with silver as cathode, the best PCE we studied is almost 3.7%. For device with gold as cathode, we have 2.8% for glass-illumination and 1.8% for metal-illumination. Further, Transmittance is up to 50%~65% within the spectrum from 650nm to 850nm. It would be our specific predominance and make us have more thoughts and choices to fulfill highly-efficient tandem cells.