Direct observation of photoinduced bound charge-pair states at an organic-inorganic semiconductor interface.
Direct observation of photoinduced bound charge-pair states at an organic-inorganic semiconductor interface.
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DOI：
10.1103/physrevlett.108.246605
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发表时间：
2012-06
影响因子：
8.6
通讯作者：
Y. Vaynzof;A. Bakulin;Simon Gélinas;R. Friend
中科院分区：
文献类型：
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作者：
Y. Vaynzof;A. Bakulin;Simon Gélinas;R. Friend
通常认为，在混合光伏器件中的有机-无机界面处的光致电荷转移立即导致一对自由电荷载流子。我们扩展了一种新的界面选择性超快“光泵推光电流探针”技术来研究混合光伏系统，并观察电子接受氧化锌和电子给体共轭聚合物之间形成的有机-无机界面上的束缚电子空穴对态。我们估计，约50%的光生电荷保持绑定，后来重组，从而阻碍了聚合物/ZnO电池的光伏性能。我们进一步证明，界面改性与富勒烯衍生物的结合电荷的分数减少到25%，这大大提高了设备的效率。
It is generally considered that photoinduced charge transfer at the organic-inorganic interfaces in hybrid photovoltaic devices immediately results in a pair of free charge carriers. We extend a novel interface-selective ultrafast "optical pump-push photocurrent probe" technique to study hybrid photovoltaic systems and observe bound electron-hole pair states at the organic-inorganic interface formed between electron-accepting zinc oxide and electron-donating conjugated polymers. We estimate that ∼50% of photogenerated charges stay bound and later recombine, thus hindering the photovoltaic performance of polymer/ZnO cells. We further demonstrate that interface modification with a fullerene derivative decreases the fraction of bound charges to ∼25%, which substantially improves the device efficiency.