Research On Organic Photovoltaic Cells With NiO Hole-Transport Layer

According to the development trend and research status of polymer organic solar cells, we find some problems and possible solutions in our studies. In this paper, the aspects as transparent conducting anode, hole transport layer, new donor and acceptor materials, and electrospun methods have been discussed. The results are as follow:1. transparent conducting anode materials(1) After the optimization of AZO, we find that the best deposition temperature is 250℃. The corresponding samples have square resistance of 31Ωsq-1 and transmittance of 85%.(2) New anode ITAZO was made on glass substrate and flexible substrate by using composite target. The topography of this anode is amorphous. The parameters of ITAZO prepared at room temperature is:square resistance of 23 ohm/square(glass substrate) and 26 ohm/square(flexible substrate), transmittance of 87.5%(glass substrate) and 86.3%(flexible substrate). The power conversion efficiency of solar cell with optimized ITAZO is 3.2%(glass substrate) and 1.66%(flexible substrate). This states that room temperature ITAZO material by composite targets method is a good substitution of anode in organic solar cell.(3) Solar cells have been made by homemade AZO, ITAZO anodes and purchased FTO anode. The results indicate that the performances are comparable with these three anodes. This implicates AZO and ITAZO are good replacement of anode again.2. NiO hole transport layer(1) We studied the whole procedure of preparation of NiO film as hole transport layer in organic solar cell by magnetron sputtering method in detail. The experiments are based on FTO glass substrate, then the best results are adopted in flexible ITO substrate. The optimized results are:room temperature,80W,30% oxygen content, 10nm thickness. And the best PCE are 3.26%(glass substrate) and 2.49% (flexible substrate). The merits of room temperature NiO are better p-style conducting and broader band gap. This will benefit electron blocking and hole transporting. Room temperature NiO will create a better condition of producing large area flexible solar cell.(2) The thickness, annealing temperature and time, topography before and after annealing, grain size of PCBM, and additive of DIO in active layer have been discussed in detail. The conclusions are:optimized thickness of active layer is about 100nm, best annealing temperature is 150℃and annealing time is 8min.(3) Solar cells based on NiO hole transport layer with various anodes, such as ITO、FTO、AZO(glass)、ITAZO(glass)、AZO(PET) and ITAZO(PET) have been compared. All samples show little changes of Jsc and FF, just Voc various from 0.53V to 0.58V. This proved again that purchased anode can be replaced by homemade anodes. Performance of solar cell with optimized AZO and NiO can reach 3.15%, which is comparable with FTO or ITO. Jsc on flexible solar cell is lower than glass substrate, but Voc and whole performance keep stable.(4) Study of electron transport layer of LiF was investigated. The Voc and FF were enhanced with layer of LiF. The optimized thickness is 1.5nm.(5) We made templates of cells in series by etch method. Solar cells in series and parallel can improve Voc and Jsc efficiently. A group of 11 LED can be drived by 8 cells in series. The area of one cell is 0.2cm2. The Voc of 4.35V and Jsc of 1.59mA were achieved of whole device.3. new donor and acceptor materials(1) The fundamental properties of PCPDTTPD were given firstly. Then we compared the performance of two system of PCPDTTPD:PCBM and P3HT:PCBM. We found that the grain size of PCBM in DCB solvent is bigger and crystallization along the proper direction. This kind of line shape and big size grain do harm to performance of solar cells, especially in Jsc. Though the Voc of 0.74V we got by this new polymer, the whole performance is inferior to P3HT system.(2) The fundamental properties of ICBA were given firstly. Then we compared the performance of two system of P3HT:PCBM and P3HT:ICBA. We found that the Voc of 0.77V and PCE of 5% can be achieved by ICBA system, which is superior to PCBM system (0.6V 4%), especially in Voc. In the mean time, we investigated the topography of ICBA before and after annealing also. In addition, the PCE of 4.46% we got with AZO anode, NiO transport layer and ICBA active layer.4. new process of electrospun on organic solar cells(1) We use new process of electrospun to fabricate NiO fiber as hole transport layer. The procedure and topography of fabrication such as solution concentration, work voltage, temperature and humidity was investigated in detail.(2) We use different NiO fiber as hole transport layer in solar cell, and we focus on the effect of performance with various fiber thickness.(3) We use NiO film+NiO fiber as hole transport layer in solar cell, and we focus on the effect of performance with various film thickness.(4) We use various topography NiO fiber as donor material, and the structure is FTO/MoOs/NiO fiber:PCBM/AI. There are no results of dot shape and line shape of NiO fiber and PCBM. The parameters of solar cell with porous shape are: Voc=0.13V, Jsc=1.5 mA/cm2, PCE= 0.01%.