Mechanism of carrier accumulation in perovskite thin-absorber solar cells

• Published in: Nature communications Vol. 4; no. 1; p. 2242
• Main Authors: Kim, Hui-Seon, Mora-Sero, Ivan, Gonzalez-Pedro, Victoria, Fabregat-Santiago, Francisco, Juarez-Perez, Emilio J., Park, Nam-Gyu, Bisquert, Juan
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 31.07.2013; Nature Publishing Group
• Subjects: 639/301/299/946; 639/766/25; Electrodes; Humanities and Social Sciences; Light; multidisciplinary; Nanoparticles; Quantum dots; Science; Science (multidisciplinary); Spectrum analysis
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms3242

Photovoltaic conversion requires two successive steps: accumulation of a photogenerated charge and charge separation. Determination of how and where charge accumulation is attained and how this accumulation can be identified is mandatory for understanding the performance of a photovoltaic device and for its further optimization. Here we analyse the mechanism of carrier accumulation in lead halide perovskite, CH 3 NH 3 PbI 3 , thin-absorber solar cells by means of impedance spectroscopy. A fingerprint of the charge accumulation in high density of states of the perovskite absorber material has been observed at the capacitance of the samples. This is, as far as we know, the first observation of charge accumulation in light-absorbing material for nanostructured solar cells, indicating that it constitutes a new kind of photovoltaic device, differentiated from sensitized solar cells, which will require its own methods of study, characterization and optimization. Understanding the accumulation of photogenerated charges in photovoltaics is crucial to developing more efficient structures. Kim et al. use impedence spectroscopy to observe charge accumulation in thin lead halide perovskite solar cells, finding a high density of states that differs from other types of cells.