Photoinduced Giant Dielectric Constant in Lead Halide Perovskite Solar Cells.
Organic-inorganic lead trihalide perovskites have emerged as an outstanding photovoltaic material that demonstrated a high 17.9% conversion efficiency of sunlight to electricity in a short time. We have found a giant dielectric constant (GDC) phenomenon in these materials consisting on a low frequency dielectric constant in the dark of the order of ε0 = 1000. We also found an unprecedented behavior in which ε0 further increases under illumination or by charge injection at applied bias. We observe that ε0 increases nearly linearly with the illumination intensity up to an additional factor 1000 under 1 sun. Measurement of a variety of samples of different morphologies, compositions, and different types of contacts shows that the GDC is an intrinsic property of MAPbX3 (MA = CH3NH3(+)). We hypothesize that the large dielectric response is induced by structural fluctuations. Photoinduced carriers modify the local unit cell equilibrium and change the polarizability, assisted by the freedom of rotation of MA. The study opens a way for the understanding of a key aspect of the photovoltaic operation of high efficiency perovskite solar cells.
†Photovoltaics and Optoelectronic Devices Group, Departament de Fisica, Universitat Jaume I, 12071 Castello, Spain.
Emilio J
EJ
Juarez-Perez
†Photovoltaics and Optoelectronic Devices Group, Departament de Fisica, Universitat Jaume I, 12071 Castello, Spain.
Rafael S
RS
Sanchez
†Photovoltaics and Optoelectronic Devices Group, Departament de Fisica, Universitat Jaume I, 12071 Castello, Spain.
Laura
L
Badia
†Photovoltaics and Optoelectronic Devices Group, Departament de Fisica, Universitat Jaume I, 12071 Castello, Spain.
Germá
G
Garcia-Belmonte
‡Center for Next Generation Dye-sensitized Solar Cells, Department of Energy Engineering, Hanyang University, Seoul 133-791, South Korea.
Yong Soo
YS
Kang
†Photovoltaics and Optoelectronic Devices Group, Departament de Fisica, Universitat Jaume I, 12071 Castello, Spain.
Ivan
I
Mora-Sero
†Photovoltaics and Optoelectronic Devices Group, Departament de Fisica, Universitat Jaume I, 12071 Castello, Spain.|§Department of Chemistry, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia.
Juan
J
Bisquert
giant dielectric constant; permittivity; perovskite; solar cell