Yuan Liu1,2,Tong Zhu2,Luke Grater2,Edward Sargent1,2
Northwestern University1,University of Toronto2
Yuan Liu1,2,Tong Zhu2,Luke Grater2,Edward Sargent1,2
Northwestern University1,University of Toronto2
Phase transitions, segregation, and decomposition of MHPs occur with the presence of humidity, light, heat, oxygen, and electrical fields. With these factors, perovskite-based devices suffer steady performance losses. Strain engineering is proven to improve the stability of perovskite materials<sup>1,2</sup>. Here, we propose to stabilize perovskite solid using perovskite quantum dot (QD) implants. The strain is created due to the manipulated lattice misalignment between the QD and matrix lattices.<br/>Prior QD-in-matrix solid studies using PbS QDs show enhanced stability of CsPbI<sub>3</sub> perovskite but failed to exploit optical properties of the perovskite matrix<sup>3,4</sup>. This prevents the use of covalent quantum dots as implants and limits the universality of this material platform.<br/>Our method is universal and practical because perovskite QDs are versatile as they can be compositionally engineered to meet bandgap and lattice parameter requirements. Given the range of lattice parameters and composition of the QD, this method estimates their capability towards stabilizing the matrix of choice before diving into lengthy synthesis.<br/>We examined mixed halide perovskite, α-CsPbI<sub>3</sub> and α-FAPbI<sub>3</sub> and found that the compressive strain introduced by QD implants enhanced the stability of the optically desired phases. For solar cell application, perovskite QD ensures a type-I band alignment where the QD features a larger bandgap, and therefore allows efficient extraction of the electron-hole pairs from the matrix perovskite. Solar cells using QD-in-mixed halide perovskite matrix solid show an open circuit voltage of 1.35 V, a power conversion efficiency of 20 %, and operation stability of over 200 hrs. This fills the gap between the configuration of QD-in-matrix and utilization of matrix perovskite for photovoltaic application, compared to prior QD-in-matrix methods.<br/><br/><b>Reference:</b><br/>(1) Moloney, E. G.; Yeddu, V.; Saidaminov, M. I. Strain Engineering in Halide Perovskites. <i>ACS Mater Lett</i> <b>2020</b>, <i>2</i> (11), 1495–1508.<br/>(2) Chen, Y.; Lei, Y.; Li, Y.; Yu, Y.; Cai, J.; Chiu, M. H.; Rao, R.; Gu, Y.; Wang, C.; Choi, W.; Hu, H.; Wang, C.; Li, Y.; Song, J.; Zhang, J.; Qi, B.; Lin, M.; Zhang, Z.; Islam, A. E.; Maruyama, B.; Dayeh, S.; Li, L. J.; Yang, K.; Lo, Y. H.; Xu, S. Strain Engineering and Epitaxial Stabilization of Halide Perovskites. <i>Nature 2020 577:7789</i> <b>2020</b>, <i>577</i> (7789), 209–215.<br/>(3) Ning, Z.; Gong, X.; Comin, R.; Walters, G.; Fan, F.; Voznyy, O.; Yassitepe, E.; Buin, A.; Hoogland, S.; Sargent, E. H. Quantum-Dot-in-Perovskite Solids. <i>Nature</i> <b>2015</b>, <i>523</i> (7560), 324–328.<br/>(4) Liu, M.; Chen, Y.; Tan, C. S.; Quintero-Bermudez, R.; Proppe, A. H.; Munir, R.; Tan, H.; Voznyy, O.; Scheffel, B.; Walters, G.; Kam, A. P. T.; Sun, B.; Choi, M. J.; Hoogland, S.; Amassian, A.; Kelley, S. O.; García de Arquer, F. P.; Sargent, E. H. Lattice Anchoring Stabilizes Solution-Processed Semiconductors. <i>Nature 2019 570:7759</i> <b>2019</b>, <i>570</i> (7759), 96–101.