Molecular-structure control of ultrafast electron injection at cationic porphyrin-CdTe quantum dot interfaces

Molecular-structure control of ultrafast electron injection at cationic porphyrin-CdTe quantum dot interfaces

Molecular-structure control of ultrafast electron injection at cationic porphyrin-CdTe quantum dot interfaces
Shawkat M. Aly , Ghada H. Ahmed , Basamat S. Shaheen , Jingya Sun , and Omar F. Mohammed
J. Phys. Chem. Lett., 6 (5), pp791–795, (2015)
Shawkat M. Aly, Ghada H. Ahmed, Basamat S. Shaheen, Jingya Sun, and Omar F. Mohammed
Ultrafast Electron Injection, Quantum Dots
2015
Charge transfer (CT) at donor (D)-acceptor (A) interfaces is central to the functioning of photovoltaic and light emitting devices. Understanding and controlling this process on the molecular level has been proven to be crucial for optimizing the performance of many energy-challenge relevant devices. Here, we report the experimental observations of controlled on/off ultrafast electron transfer (ET) at cationic porphyrin-CdTe quantum dot (QD) interfaces using femto- and nanosecond broadband transient absorption (TA) spectroscopy. The time-resolved data demonstrate how one can turn on/off the electron injection from porphyrin to the CdTe QDs. With careful control of the molecular structure, we are able to tune the electron injection at the porphyrin-CdTe QD interface from zero to very efficient and ultrafast. In addition, our data demonstrate that the ET process occurs within 120 femtoseconds, which is one of the fastest times recorded for organic photovoltaics.



DOI: 10.1021/acs.jpclett.5b00235