Study On The Preparation And Performance Of Spraying-based Polymer Solar Cells

Polymer-based organic solar cells have attracted considerable interest owing to their low-cost, simple solution processing and flexibility. With the improving of the power conversion efficiency, it become more and more important to large-scale production of organic solar cells. In recent years, people developed many techniques compatible with roll to roll process for the preparation of large area organic solar cells. Spraying technology is widely used for coating of polymer films owing to its simple equipment, high material utilization rate, less requirement on the substrate. Several groups have reported the fabrication of OSCs using a spray-coating method with results similar to those of spin-coating. These efforts have focused mainly on process development with a small cell size but not the key advantage of that process, i.e. large-area OSC application. Few people applied spraying technology to the preparation of large-area organic solar cells.In this paper, organic solar cells based on mature material and structure were fabricated. The performance of small area devices was improved by optimizing spraying conditions of the anode buffer layer and the active layer. Furthermore, the spraying technology was applied to the preparation of large-area organic solar cells and the structure and process for large-area organic solar cells were explored. The work includes the following content:Ⅰ. The effects of spraying flow rate, solution concentration volume fraction of original PEDOTrPSS solution) and substrate temperature in preparation of poly(3,4-ethylenedioxyth iophene):poly(styrenesulfona-te)(PEDOT:PSS) layer on the performance of the device were explored and discussed systematically. When the spraying flow rate was 100ul/min, the concentration of PEDOT:PSS solution was 66.7% and the substrate temperature was 100℃, the device showed an optimal performance and its power conversion efficiency increased from the initial 0.79% to 1.94%.Ⅱ. The effects of film thickness, substrate temperature and annealing conditions in preparation of poly(3-hexylthiopene):1-(3-methoxy-carbonyl)-propyl-1-phenyl-(6,6) C60(P3HT:PCBM) layer on the performance of organic solar cells were explored and discussed systematically. The experimental results showed that:when the film thickness of the active layer was 260nm, the substrate temperature was 130℃ and the annealing condition is a 130℃ 60s pre-thermal annealing combined with a 130℃ 5min post thermal annealing, the device showed the best performance and its power conversion efficiency increased from the initial 0.13% to 2.58%.Ⅲ. Influence mechanism of the device effective area on the device performance was investigated and the structure and process for preparation of large area organic solar cells were explored. We find that the large area devices prepared with a series-parallel structure showed the best performance. By optimizing the spraying direction, the power conversion efficiency of the 11.2cm2 large area device was improved from 0.91% to 1.82%.The investigation of the spraying process to prepare the organic anode buffer layer and the active layer in this paper provides a valuable reference for the preparation of organic solar cells by spraying. At the same time, the large area organic solar cell with a s series-parallel structure prepared by spraying coating showed a good device performance, which demonstrates the status and development prospects of the spraying technology in the mass production of organic solar cells.