Abstract
Perovskite materials have experienced an impressive improvement in photovoltaic performance due to their unique combination of optoelectronic properties. Their remarkable progression, facilitated by the use of different device architectures, compositional engineering, and processing methodologies, contrasts with the lack of understanding of the materials properties and interface phenomena. Here we directly target the interplay between the charge-transporting layers (CTLs) and open-circuit potential (VOC) in the operation mechanism of the state-of-the-art CH3NH3PbI3 solar cells. Our results suggest that the VOC is controlled by the splitting of quasi-Fermi levels and recombination inside the perovskite, rather than being governed by any internal electric field established by the difference in the CTL work functions. In addition, we provide novel insights into the hysteretic origin in perovskite solar cells, identifying the nature of the contacts as a critical factor in defining the charge accumulation at its interface, leading to either ionic, electronic, or mixed ionic-electronic accumulation.
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•The interplay between the charge-transporting layers and open-circuit potential•The nature of the contacts: a critical factor for the interfacial charge accumulation•The quasi-Fermi level splitting and recombination inside the perovskite rules the VOC•The electric field is not the dominant extraction mechanism for the photocarriers
Perovskite lead halides are extraordinary low-cost materials and outstanding candidates for an efficient electricity generation. After only a few years of research, perovskite-based technology has been demonstrated to rival those of the prevailing inorganic counterparts, with the advantage of being processed through a variety of easy and cheap fabrication techniques. Nevertheless, such an unprecedented rise in efficiency contrasts with the lack of understanding of the materials properties and interface phenomena, which represents one of the major challenges before its commercialization. Here we provide fundamental insights into the operation mechanism of the state-of-the-art perovskite solar cells, revealing crucial findings on the open-circuit potential VOC and the hysteretic origin in these cells.
Perovskite materials are becoming a major player for the future energy scenario. In only a few years, they have demonstrated extraordinary capabilities for optoelectronic applications, promising the highest efficiency at the lowest cost. However, despite the numerous studies reported in the literature, the photophysical behavior and device physics for this new technology remain unclear. Here we reveal fundamental insights into the operation mechanism of the state-of-the-art perovskite solar cells, shedding light on the origins of the open-circuit potential and the hysteretic behavior.