Dissociative Host-Dopant Bonding Facilitates Molecular Doping in Halide Perovskites
Luis Lanzetta, Luca Gregori, Luis Huerta Hernandez, Anirudh Sharma, Stefanie Kern, Anna M. Kotowska, Abdul‐Hamid Emwas, Luis Gutiérrez‐Arzaluz, David J. Scurr, Matthew Piggott, Daniele Meggiolaro, Md Azimul Haque, Filippo De Angelis, Derya Baran
Abstract
Molecular doping is a promising strategy to fine-tune the electronic properties of halide perovskites and accelerate their implementation in next-generation optoelectronics. However, a deeper understanding of the role of host-dopant interactions in these systems is needed to fully exploit the potential of this avenue. Herein, we demonstrate a surface post-treatment strategy employing n-type molecular dopant n-DMBI-H to modulate free hole density in p-type CH 3 NH 3 Sn 0.75 Pb 0.25 I 3 films. We show that the adsorption of n-DMBI-H on surface Sn atoms, followed by the dissociation of an electron-donating hydride from the dopant, facilitates charge transfer to the perovskite and hole trapping at the dissociated hydride. We identify this mechanism as a key factor dictating doping compensation in perovskites, allowing carrier density control within nearly 1 order of magnitude via the dissociated molecular dopant located at film surfaces and grain boundaries. We then exploit n-DMBI-H in perovskite/transport layer junctions, achieving reduced carrier losses and improved contact selectivity and performance in p-i-n, Sn-rich perovskite solar cells. We expect this work to provide carrier density tuning guidelines for a broad range of tin-based perovskite applications.