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Chemically Orthogonal Hole Transport Layer for Efficient Colloidal Quantum Dot Solar Cells



Margherita Biondi, Min-Jae Choi, Olivier Ouellette, Se-Woong Baek, Petar Todorovi?, Bin Sun, Peicheng Li, Ahmad R. Kirmani, Laxmi Chiluka, Lee J. Richter, Sjoerd Hoogland, Zheng-Hong Lu, F. Pelayo Garc?a de Arquer, Edward H. Sargent, Mingyang Wei


Colloidal quantum dots (CQDs) are of interest in light of their solution-processing and bandgap tuning. Advances in the performance of CQD optoelectronic devices require fine control over the properties of each layer in the device materials stack. This is particularly challenging in the present best CQD solar cells, since these employ a p-type hole-transport layer (HTL) implemented using 1,2-ethandithiol (EDT) ligand exchange on top of the CQD active layer. We establish that the high reactivity of EDT causes a severe chemical modification to the active layer that deteriorates charge extraction. By combining elemental mapping with the spatial charge collection efficiency in CQD solar cells, we determine the key materials interface dominating the subpar performance of prior CQD PV devices. This motivates us to develop a chemically-orthogonal HTL that consists of malonic-acid crosslinked CQDs. The new crosslinking strategy preserves the surface chemistry of the active layer beneath, and at the same time provides the needed efficient charge extraction. The new HTL enables a 1.4x increase in charge carrier diffusion length in the active layer; and as a result leads to an improvement in power conversion efficiency to 13.0% compared to EDT standard cells (12.2%).
Advanced Materials


Biondi, M. , Choi, M. , Ouellette, O. , Baek, S. , Todorovi?, P. , Sun, B. , Li, P. , Kirmani, A. , Chiluka, L. , Richter, L. , Hoogland, S. , Lu, Z. , Garc?a de Arquer, F. , Sargent, E. and Wei, M. (2020), Chemically Orthogonal Hole Transport Layer for Efficient Colloidal Quantum Dot Solar Cells, Advanced Materials, [online],, (Accessed July 17, 2024)


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Created March 19, 2020, Updated October 12, 2021