Polarization Controlled Photocurrent in Perovskite CsGeX3 (X = Cl, Br, I)

The anomalous photocurrent in perovskite CsGeX3 (X = Cl, Br, I), which is enhanced by spontaneous polarization, has recently attracted the attention of both theoretical and experimental researchers. However, the underlying mechanism of ferroelectric-optical coupling remains an open question that requires further investigation. The polarization displacements in our grown single-crystal perovskite structure in CsGeX3 (X = Cl, Br, I) are from the Ge2+ ion distortion based on the calculation of the synchrotron radiation X-ray pair distribution function. Furthermore, we carry out the simulations of the photocurrent in CsGeX3 halides by means of nonequilibrium Green's function (NEGF) method. To examine the effect of polarized light irradiation on the CsGeX3 structures, we calculated the induced photocurrents with different transport directions. The theoretical results indicated that the photocurrents were influenced by diverse halogens at the X site in perovskite CsGeX3.