Jiahuan Zhang

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Intermediate phase engineering of halide perovskites for photovoltaics

Ulf Anders Hagfeldt, Zaiwei Wang, Wanchun Xiang, Jiahuan Zhang

Metal halide perovskites serving as one of the most promising photovoltaic materials are gaining considerable attention worldwide. For achieving high performance as well as long-term stability of the perovskite solar cells (PSCs), a good quality of perovskite film featuring in smooth, pinhole-free morphology, full coverage over substrates, good heterojunction contacts, and stable photoactive phase is of great importance. During solution fabrication for perovskite films, intermediate phase, which refers to the state of precursor composition before final annealing, plays an essential role in determining the film quality, especially in the state-of-theart PSCs. In this review, we summarize the research involving mechanism and applications of intermediate phase engineering (IPE) processes in various solution-processing technologies. The challenges of IPE are further discussed, and perspectives are provided for developing high-performance PSCs via IPE.

CELL PRESS2022

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In the last decade, halide perovskites have emerged as new semiconductors that revolutionize the photovoltaic field. Among this family of materials, all-inorganic halide perovskites are becoming a research paradigm because of their outstanding photophysical properties combined with the potential of long-term stabilities against moisture and thermal stresses in practical applications. By forming high-quality inorganic halide perovskite thin films and stabilizing the three-dimensional perovskite phases, in the past few years, the state-of-the-art inorganic perovskite solar cells have achieved a power conversion efficiency of 20.37% and a promising long-term operation stability. In this review, based on the latest research progress of inorganic halide perovskites for photovoltaics, we summarized (1) the crystal structural, optical, and photophysical properties of materials; (2) the film formation methods; and (3) the stabilization strategies of inorganic perovskite phase, to provide useful guideline for fabricating devices with further enhanced performance and stability, and promoting commercial applications.

ELSEVIER2021

Intermediate Phase Enhances Inorganic Perovskite and Metal Oxide Interface for Efficient Photovoltaics

Anand Agarwalla, Claudia Esther Avalos, Brian Irving Carlsen, David Lyndon Emsley, Wei Guo, Ulf Anders Hagfeldt, Dominik Józef Kubicki, Yuhang Liu, Haizhou Lu, Aditya Mishra, Mona Shasti, Wolfgang Richard Tress, Zaiwei Wang, Zishuai Wang, Wanchun Xiang, Jiahuan Zhang

Interfacial modification is crucial to fully develop the potential of semiconductor devices, including the revolutionary halide perovskite-based optoelectronics, such as photovoltaics, light-emitting diodes, and photodetectors. The all-inorganic halide perovskites, which are potential long-term stable photovoltaic materials, are suffering from poor interfacial contact with metal oxide charge-selective layer, severely limiting the power conversion efficiency and stability of inorganic perovskite solar cells. Here, we propose an intermediate-phase engineering strategy to improve the inorganic perovskite/metal oxide interface by utilizing volatile salts. The introduction of organic cations (such as methylammonium and formamidinium), which can be doped into the perovskite lattice, leads to the formation of an organic-inorganic hybrid perovskite intermediate phase, promoting a robust interfacial contact through hydrogen bonding. A champion CsPb(I0.75Br0.25)(3)-based device with a power conversion efficiency of 17.0% and an open-circuit voltage of 1.34 V was realized, implying that a record of over 65% of the Shockley-Queisser efficiency limit is achieved.

CELL PRESS2020