Yu-Wu Zhong

Bio: Yu-Wu Zhong is an academic researcher from Chinese Academy of Sciences. The author has contributed to research in topics: Perovskite (structure) & Photovoltaics. The author has an hindex of 1, co-authored 1 publications receiving 3 citations.

Design of small molecular hole-transporting materials for stable and high-performance perovskite solar cells

Abstract: Perovskite solar cells represent one of the most exciting developments in photovoltaics in the past decade, with the power conversion efficiencies of over 25% being achieved to date. In high-performance perovskite solar cells, hole-transporting materials are generally employed to extract and transport holes from perovskite. Among them, small molecular hole transporting materials have attracted intense interest due to their tunable energy levels, structural variety, and simple synthesis. The commonly used hole-transporting material is 2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenyl amino)-9,9′-spirobifluorene (spiro-OMeTAD). Considering the high synthetic cost of spiro-OMeTAD and the device stability issue associated with the use of dopants, much research has been focused on the development of alternative high-performance hole-transporting materials. Herein, this review summarizes the recent developments in highly efficient small molecular hole-transporting materials with a power conversion efficiency close to or over 20%. On the basis of their structural features, three categories of small molecules are identified and discussed as highly efficient hole-transporting materials: spiro molecules with new terminal groups or a new spiro skeleton, star-shaped small molecular hole-transporting materials with three or four branches, and linear hole-transporting materials with a D-A, D-π-D, D-A-D, or D-A-π-A-D structure. The relationships of the optoelectronic properties of these hole-transporting materials and the device performance are discussed, with a comparison to those of model compounds in some cases. Finally, an outlook is addressed on the future development of hole-transporting materials for high-performance perovskite solar cells. We hope that this review can provide important guidance for the design and synthesis of new hole-transporting materials and finally help to promote the commercialization of perovskite solar cells.

Conjugation Engineering of Spiro-Based Hole Transport Materials for Efficient and Stable Perovskite Solar Cells

Abstract: The spiro-type hole transport materials (HTMs) highly depend on the dopants, which increase the hygroscopicity and damage the stability of perovskite solar cells (PSCs). Herein we propose an effective linearization strategy and conjugate engineering modulation to improve the hole mobility and hydrophobicity of spiro-type HTMs. It is found that the spiro-type HTMs with a larger conjugation unit outperforms the short ones with respect to the power conversion efficiency (PCE) and long-term stability, regardless of whether or not the dopants are used. Due to good hole transport and film formation properties, the doped M6-F exhibits high efficiency in both large-area (1.01 cm2, 20.31%) and small-area (0.1 cm2, 22.17%) devices. Moreover, a PSC based on dopant-free M6-F yields an efficiency of 21.21% (stabilized PCE is 20.59%). This work provides a rational and effective way to break the bottleneck of developing spiro-type HTMs.

Recent progress in perovskite solar cells: material science

Abstract: Perovskite solar cells represent a promising third-generation photovoltaic technology with low fabrication cost and high power conversion efficiency. In light of the rapid development of perovskite materials and devices, a systematic survey on the latest advancements covering a broad range of related work is urgently needed. This review summarizes the recent major advances in the research of perovskite solar cells from a material science perspective. The discussed topics include the devices based on different type of perovskites (organic-inorganic hybrid, all-inorganic, and lead-free perovskite and perovskite quantum dots), the properties of perovskite defects, different type of charge transport materials (organic, polymeric, and inorganic hole transport materials and inorganic and organic electron transport materials), counter electrodes, and interfacial materials used to improve the efficiency and stability of devices. Most discussions focus on the key progresses reported within the recent five years. Meanwhile, the major issues limiting the production of perovskite solar cells and the prospects for the future development of related materials are discussed.