Photo-electronic Hybrids Research Center, Korea Institute of Science and Technology , Seoul 136-791, Republic of Korea.
ACS Appl Mater Interfaces. 2014 Jan 8;6(1):333-9. doi: 10.1021/am404381e. Epub 2013 Nov 25.
We report the achievement of a power conversion efficiency (PCE) improvement in P3HT:PCBM-based bulk-heterojunction type polymer solar cells using photocrosslinked P3HT (c-P3HT) as the electron blocking/hole extraction layer and titanium oxide nanoparticles (TiO2) as the hole blocking/electron extraction layer. Devices prepared with a 20 nm thick c-P3HT layer showed an improved PCE of 3.4% compared to devices prepared without the c-P3HT layer (PCE = 3.0%). This improvement was attributed to an extension in the carrier lifetime and an enhancement in the carrier mobility. The incorporation of the c-P3HT layer lengthened (by more than a factor of 2) the carrier lifetime and increased (by a factor of 5) the hole mobility. These results suggest that the c-P3HT layer not only prevented non-geminate recombination but it also improved carrier transport. The PCE was further improved to 4.0% through the insertion of a TiO2 layer that acted as an effective hole-blocking layer at the interface between the photoactive layer and the cathode. This work demonstrates that the incorporation of solution-processable hole and electron blocking/extraction layers offers an effective means for preventing nongeminate recombination at the interfaces between a photoactive layer and an electrode in bulk-heterojunction-type polymer solar cells.
我们报告了使用光交联 P3HT（c-P3HT）作为电子阻挡/空穴萃取层和氧化钛纳米粒子（TiO2）作为空穴阻挡/电子萃取层，在基于 P3HT:PCBM 的体异质结型聚合物太阳能电池中实现功率转换效率（PCE）提高的成就。与没有 c-P3HT 层的器件（PCE = 3.0%）相比，使用 20nm 厚的 c-P3HT 层制备的器件显示出提高的 PCE 为 3.4%。这种改进归因于载流子寿命的延长和载流子迁移率的增强。c-P3HT 层的掺入使载流子寿命延长（超过 2 倍），并使空穴迁移率增加（增加 5 倍）。这些结果表明，c-P3HT 层不仅防止了非复合复合，而且改善了载流子输运。通过插入 TiO2 层进一步将 PCE 提高到 4.0%，TiO2 层在活性层和阴极之间的界面处充当有效的空穴阻挡层。这项工作表明，在体异质结型聚合物太阳能电池中，在活性层和电极之间的界面处掺入溶液处理的空穴和电子阻挡/萃取层是防止非复合复合的有效手段。
