Study On The Interfaciai Modification Of Polymer Solar Cells

Interfacial modification play a key role in fabricating multilayerarchitecture devices, improving the PCE of polymer solar cells (PSCs) andoptimizing the stability and lifetime of devices. However there still someissues to be improved: the fabrication of interfacial layer shouldcompatible with solution processed PSC. Improve the stability of materialsof interfacial layer. Avoid the post treatment such as thermal annealingwhich make damage to active layer. Developing novel interfacial materialswhich compatible with most materials systems.In this thesis, we made efforts to improve above aspects:1. We introduce PAH-D layer to modify the active layer surface ofP3HT:PCBM and convert the hydrophobic surface to amphiphilic and a aqueousPEDOT:PSS PH500can be deposited on surface of active layer as electrode.All-spin-coating vacuum-free processed semi-transparent PSCs wasfabricated. PAH-D is a amphiphilic self assembly molecules which can bedeposited onto both hydrophobic or hydrophilic surface. By introducingamphiphilic PAH-D as interfacial layer, we can convert the hydrophobic orhydrophilic surface to amphiphilic. So solution with different surfaceenergy can be deposited layer by layer according solution process such asspin coating which providing a method for constructing multilayer solutionprocess device architectures and making all solution processed PSCs. 2. The interface between polymer and nano crystals （NCs） was optimizedby using in-suit polymerization, introducing the SAM modifier to modifythe surface of NCs. By in-suit polymerization, the phase separation betweenpolymer and NCs can be controlled and avoid the large scale aggressioncaused by the naturally differences of their surface energy. The surfacemodification by SAM modifier can construct an aligned energy levelstructures and beneficial for the charge transport as well as optimize themorphology of PSCs.3. We make the preformation of P(VDF-TrFE50:50) NCs by a solutionchemistry method and their application in low bandgap PSCs to avoid hightemperature, post-deposition thermal annealing. To the best of ourknowledge, this is the first time that ferroelectric polymer NCs weresynthesized by a very simple solution method and applied in FE-OPVs. Thesize of P(VDF-TrFE) NPs and their crystallinity can be easily controlledbefore they are inserted into the PSCs. The coverage of the P(VDF-TrFE)ferroelectric interlayer can then be precisely manipulated to maximize theefficiency of FE-OPVs. It is easy to deposit the NC layer using solutionprocess. The best PCE reached6.64%, which is among the highest valuesreported for PCDTBT-based solar cells.