Dresden 2017 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 25: Fundamentals of Perovskite Photovoltaics IV (joint session CPP/DS/HL)

CPP 25.3: Talk

Tuesday, March 21, 2017, 14:45–15:00, ZEU 222

Fill factor optimization strategies in efficient, stable triple cation perovskite solar cells — •Martin Stolterfoht, Christian Wolff, Yochai Amir, Andreas Paulke, and Dieter Neher — Institute of Physics and Astronomy, University of Potsdam, Potsdam-Golm, Germany

Perovskite solar cells (PSCs) now compete with their inorganic counterparts in terms of power conversion efficiency. To advance this technology even further, more insights into the physical mechanisms that define the bias dependence of the photocurrent are required. In this work, we varied the organic electron/hole transport layers (ETL/HTL) thickness in efficient triple cation PSCs and studied the charge carrier recombination and transit through the device. Using resistance dependent photovoltage (RPV), we identify the transit time through the transport layers as key figure of merit for maximizing the fill factor (FF) and the overall photovoltaic performance. The results are complemented by intensity dependent photocurrent measurements which elucidate the role of the HTL thickness on the bias dependence of the recombination losses and recombination order. By optimizing the transit time through the HTL (undoped PTAA) we demonstrate efficiencies under solar AM1.5G conditions of up to 20.4% with high FFs of 80%. The reported cells also exhibit excellent stability under light illumination and stability in air, even without encapsulation. However, further improving the FF via a continuous reduction of the HTL leads to significant open-circuit voltage losses which highlights the challenge to simultaneously optimize the FF and open-circuit voltage.