Wednesday, May 2, 2018
Abstract-Ultrafast zero-bias photocurrent and terahertz emission in hybrid perovskites
Petr A. Obraztsov, Dmitry Lyashenko, Pavel A. Chizhov, Kuniaki Konishi, Natsuki Nemoto, Makoto Kuwata-Gonokami, Eric Welch, Alexander N. Obraztsov, Alex Zakhidov,
Methylammonium lead iodide is a benchmark hybrid organic perovskite material used for low-cost printed solar cells with a power conversion efficiency of over 20%. Nevertheless, the nature of light–matter interaction in hybrid perovskites and the exact physical mechanism underlying device operation are currently debated. Here, we report room temperature, ultrafast photocurrent generation, and free-space terahertz emission from unbiased hybrid perovskites induced by femtosecond light pulses. The polarization dependence of the observed photoresponse is consistent with the bulk photovoltaic effect caused by a combination of injection and shift currents. Observation of this type of photocurrents sheds light on the low recombination and long carrier diffusion lengths arising from the indirect bandgap in CH3NH3PbI3. Naturally ballistic shift and injection photocurrents may enable third-generation perovskite solar cells with efficiency exceeding the Shockley–Queisser limit. The demonstrated control over photocurrents with light polarization also opens new venues toward perovskite spintronics and tunable THz devices.