Study On The Influence Of The Fabrication Conditions On PTB7/PC₇₁BM Organic Solar Cell Performance

Energy shortage and environmental pollution have become a big threat to humansurvival and development. Polymer bulk hetero-junction organic solar cells (OSCs forshort) have the advantages of low cost and no pollution thus attracting more and moreattention. The PTB7/PC71BM polymer OSCs have high Jsc(short-circuit current) andPCE(Power Convert Efficiency) due to its excellent photon absorption capacity, thusdeserve detailed study.This essay’s main contents are “the fabrication and Optimization of PTB7/PC71BMpolymer OSCs and study on the fabrication conditions’ influence on the performance ofthe cell”. The conclusions are as follows:1. Thermal annealing will cause serious damage on the morphology ofPTB7/PC71BM active layer, thus making a significant degradation in cell performance.2. In order to save material, the active layer is spin-coated as follows: Rotate thesample, use the pipette to take50uL mixed solution and drip on the sample. Thisapproach not only saves material, but also slightly enhance the cell performanceaccording to the experiment results.3. After spin-coating the active layer, cell performance using following methods isbetter in contrast to baking under80℃for10min: place the sample in a glove box for2hours, then place it in vacuum for10minutes, and finally back into the glove box for2days or more.4. The rotate speed has a great influence on the thickness and morphology of thespin-coated active layer. According to the literature we try four rotate speeds:800rpm,900rpm,1000rpm and1100rpm, the experiment results show that as the rotate speedgoes higher, the thickness of the active layer decreases and so does the light absorptionand Jsc, but the smaller thickness of the active layer makes the transportation andcollection of the free carriers easier and the FF (Fill Factor) higher.5. In order to improve the reliability of the PTB7/PC71BM polymer OSCs, wefabricate the ZnO inverted polymer OSCs, the experiment results show this structuredoes enhance cell’s reliability, Voc remains almost unchanged and PCE is59.5%oforiginal value after exposing in air for5days. But the same structure with P3HT/PCBMcan withstand exposing in air for1~2years, so the PTB7/PC71BM cell’s reliability stillneeds to improve.