Study On Production Process And Decay Properties Of Organic Solar Cell Based On P3HT And PCBM

Compared with traditional solar cells, the organic polymer solar cells show significant advantages,such as the sources of materials, light weight, simple fabrication process, low cost, and large areaproduction. Due to be the great market prospect, the research on organic solar cell has become aninteresting and hot topic in recent years.The thesis focuses on the active layer made of organic materials, which the poly （3-hexylthiophene）（P3HT） is as a donor and the [6,6]-phenyl C61butyric acid methyl ester （PCBM） as acceptor. Theattenuated laws of the performance of open circuit voltage, short-circuit current, power conversionefficiency （PCE） and fill factor （FF） were detailed studied along with time for the un-encapsulated organicsolar cell. Specially, the performance of the organic solar cell was measured on different annealingtemperatures. By modifying the usual cell structure, an improvement cell which can improve theperformance of organic solar cells was manufactured in our works.Firstly, the author studied the etch method of the transparent anode made of indium tin oxide （ITO）. Itwas found that the morphology of ITO film was strongly affected by many factors in the etching processing,such as the substrate cleaning, spin-coating conditions of the photo resist, the pre-baking temperature andtime, the exposure and development time, as well as the influence of acid etching conditions. Byexperiment and measurement, we obtained an optimized condition, of which the suitable speed of spincoating is2000pm/s, the pre-baking temperature is80℃for20min., the exposure and development timeare17s and2min., respectively. As a result, the nice electrode morphology is obtained when theproportion of HCl and H₂O is3:1by volume using catalyst FeCl₃.H₂O.Secondly, the author further studied the performance degrades as time goes for the un-encapsulatedorganic solar cell. The result showed that both the open voltage and short-circuit current change with shelftime as a function of normative quadratic exponential, respectively. For the deterioration of the powerconversion efficiency with shelf time, a cubic exponential relationship is obtained. However, ofextraordinary is, the changes of the fill factor take on zigzag shape with shelf time. As a result, one canconclude that the performance of the organic solar cell will decay quickly and markedly if the cell is un-encapsulated. Therefore, the problems concerning lifetime and stability of the organic solar cell shouldbe taken attention in practice.Thirdly, the author found that the active layer can improve the transmittance of the light and reducelight reflectivity by annealing. The active layer was annealized at different temperatures:80℃,120℃and140℃. It showed that crystalloid of the active layer is the best at140℃by XRD analysis. The powerconversion efficiency of organic solar cells was the best when active layer was annealed at140℃.At last, the author added a layer of P3HT between the aluminum electrode and the active layer basedon P3HT: PCBM to study the performance of the organic solar cell. The results indicated that open circuitvoltage，short-circuit current density and power conversion efficiency increased apparently. It’s notable thatopen voltage increased more than50%. Meanwhile, fill factor showed a decreasing trend.