Charting the Irreversible Degradation Modes of Low Bandgap Pb‐Sn Perovskite Compositions for De‐Risking Practical Industrial Development

Advanced Energy Materials Wiley 14:10 (2024)

Authors:

Christina Kamaraki, Matthew T Klug, Vincent J‐Y Lim, Nourdine Zibouche, Laura M Herz, M Saiful Islam, Christopher Case, Laura Miranda Perez

Trace Water in Lead Iodide Affecting Perovskite Crystal Nucleation Limits the Performance of Perovskite Solar Cells.

Advanced materials (Deerfield Beach, Fla.) 36:7 (2024) e2310237

Authors:

Renjun Guo, Qiu Xiong, Aleksander Ulatowski, Saisai Li, Zijin Ding, Tianxiao Xiao, Suzhe Liang, Julian E Heger, Tianfu Guan, Xinyu Jiang, Kun Sun, Lennart K Reb, Manuel A Reus, Andrei Chumakov, Matthias Schwartzkopf, Minjian Yuan, Yi Hou, Stephan V Roth, Laura M Herz, Peng Gao, Peter Müller-Buschbaum

Abstract:

The experimental replicability of highly efficient perovskite solar cells (PSCs) is a persistent challenge faced by laboratories worldwide. Although trace impurities in raw materials can impact the experimental reproducibility of high-performance PSCs, the in situ study of how trace impurities affect perovskite film growth is never investigated. Here, light is shed on the impact of inevitable water contamination in lead iodide (PbI2 ) on the replicability of device performance, mainly depending on the synthesis methods of PbI2 . Through synchrotron-based structure characterization, it is uncovered that even slight additions of water to PbI2 accelerate the crystallization process in the perovskite layer during annealing. However, this accelerated crystallization also results in an imbalance of charge-carrier mobilities, leading to a degradation in device performance and reduced longevity of the solar cells. It is also found that anhydrous PbI2 promotes a homogenous nucleation process and improves perovskite film growth. Finally, the PSCs achieve a remarkable certified power conversion efficiency of 24.3%. This breakthrough demonstrates the significance of understanding and precisely managing the water content in PbI2 to ensure the experimental replicability of high-efficiency PSCs.

Compositional Transformation and Impurity‐Mediated Optical Transitions in Co‐Evaporated Cu2AgBiI6 Thin Films for Photovoltaic Applications

Advanced Energy Materials Wiley (2024)

Authors:

Benjamin WJ Putland, Marcello Righetto, Heon Jin, Markus Fischer, Alexandra J Ramadan, Karl‐Augustin Zaininger, Laura M Herz, Harry C Sansom, Henry J Snaith

The Role of the Organic Cation in Developing Efficient Green Perovskite LEDs Based on Quasi‐2D Perovskite Heterostructures

Advanced Functional Materials Wiley (2023)

Authors:

Alexandra J Ramadan, Woo Hyeon Jeong, Robert DJ Oliver, Junke Jiang, Akash Dasgupta, Zhongcheng Yuan, Joel Smith, Jae Eun Lee, Silvia G Motti, Olivia Gough, Zhenlong Li, Laura M Herz, Michael B Johnston, Hyosung Choi, Jacky Even, Claudine Katan, Bo Ram Lee, Henry J Snaith

Alloying Effects on Charge-Carrier Transport in Silver-Bismuth Double Perovskites.

The journal of physical chemistry letters 14:46 (2023) 10340-10347

Authors:

Marcello Righetto, Sebastián Caicedo-Dávila, Maximilian T Sirtl, Vincent J-Y Lim, Jay B Patel, David A Egger, Thomas Bein, Laura M Herz

Abstract:

Alloying is widely adopted for tuning the properties of emergent semiconductors for optoelectronic and photovoltaic applications. So far, alloying strategies have primarily focused on engineering bandgaps rather than optimizing charge-carrier transport. Here, we demonstrate that alloying may severely limit charge-carrier transport in the presence of localized charge carriers (e.g., small polarons). By combining reflection-transmission and optical pump-terahertz probe spectroscopy with first-principles calculations, we investigate the interplay between alloying and charge-carrier localization in Cs2AgSbxBi1-xBr6 double perovskite thin films. We show that the charge-carrier transport regime strongly determines the impact of alloying on the transport properties. While initially delocalized charge carriers probe electronic bands formed upon alloying, subsequently self-localized charge carriers probe the energetic landscape more locally, thus turning an alloy's low-energy sites (e.g., Sb sites) into traps, which dramatically deteriorates transport properties. These findings highlight the inherent limitations of alloying strategies and provide design tools for newly emerging and highly efficient semiconductors.