有机太阳能电池原理的相关问题？教科书上的话：”异质节有机太阳能电池，激子产生后，因为激子的移动距离有限，所以active layer必须做的很薄，但是这就导致太阳光的吸收效率降低“我的问题是：为什么active layer薄，会导致太阳光的吸收效率变低？教科书上的原话：The distance that excitons can diffuse before recombination is called the excitondiffusion length.Common exciton diffusion lengths in organic semiconductors are veryshort, at a few tens of nanometers [7, 20]. Excitons generated at a distance from theheterojunction longer than this length will recombine before reaching the hetero-junction, resulting in lower exciton dissociation ef?ciency. Hence, the active layershave to be kept thin in order to ensure that phase separation between the donor andacceptor is within the exciton dissociation length. However, a thin active layer resultsin a serious tradeoff of low absorption ef?ciency. Therefore, it is important to have alarge interface area for exciton dissociation and adequate phase separation to ensureef?cient exciton dissociation. To achieve this, innovative device architectures such asthe bulk heterojunction and nanostructured active layers have been suggested.查看更多3个回答 . 3人已关注
关于负载型核壳结构催化剂制备的求助。？各位大神，? ?? ???最近看了好几篇关于负载型核壳结构 催化剂 的制备问题，对其中一些问题很是想不通，问有了解的帮忙看看；? ?? ???负载型核壳催化剂一般是两套方法：? ?? ? 1、先合成核壳结构，在负载到载体上。但我感觉这种能负载上么，即使能负载上但感觉作用很弱，不稳定吧？? ?? ? 2、先将一种金属负载上，还原成单质，利用Kirkendall effect, 和galvanic replacement reaction (GRR), 让第二种金属刻蚀到第一种金属外面形成核壳结构。举个例子，一篇文献里的做Ni@Pd/C的催化剂，方法大概是：? ???“To a flask was added??VXC-72 carbon, Ni(NO3)2, sodium citrate, and water. The mixture was ultrasonicated for 30 min.Then, a freshly prepared, ice-cold NaBH4 solutionwas added into the above mixture within 5 min. The resultant mixture was stirred magnetically for 2 h. Thereafter, Na2PdCl4 was added drop-wise into the mixture within 2 min. The mixture was stirred for another 3 h." 对这我有好几个不太明白：（1）加了NaBH4是过量的，但是也没洗也没干燥，就加入了后面的Na2PdCl4，难道NaBH4不会与Na2PdCl4反应吗？（2）最重要的是，即使不考虑NaBH4的问题，加入的Na2PdCl4为什么就会与Ni反应，而不是直接吸附在 活性炭 上（普通的浸渍法做Pd/C的时候就是直接让C吸附Na2PdCl4后煅烧还原啊，而且很容易吸附吧）。望相关研究方向的人帮忙解答解答，谢谢！查看更多1个回答 . 1人已关注
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