Webb, ThomasThomasWebbHaque, SaifSaifHaqueWestbrook, robertrobertWestbrookMacdonald, thomasthomasMacdonald2022-05-232022-05-232022-07-14Advanced Energy Materials, 2022, 12 (26), pp.1-141614-6832http://hdl.handle.net/10044/1/96938Over the last decade, 2,2″,7,7″-Tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9′-spirobifluorene (spiro-OMeTAD) has remained the hole transporting layer (HTL) of choice for producing high efficiency perovskite solar cells (PSCs). However, PSCs incorporating spiro-OMeTAD suffer significantly from dopant induced instability and non-ideal band alignments. Herein, a new approach is presented for tackling these issues using the functionality of organometallocenes to bind to Li+ dopant ions, rendering them immobile and reducing their impact on the degradation of PSCs. Consequently, significant improvements are observed in device stability under elevated temperature and humidity, conditions in which ion migration occurs most readily. Remarkably, PSCs prepared with ferrocene retain 70% of the initial power conversion efficiency (PCE) after a period of 1250 h as compared to only 8% in the control. Synergistically, it is also identified that ferrocene improves the hole extraction yield at the HTL interface and reduces interfacial recombination enabling PCEs to reach 23.45%. This work offers a pathway for producing highly efficient spiro-OMeTAD devices with conventional dopants via addressing the key challenge of dopant induced instability in leading PSCs.© 2022 The Authors. Advanced Energy Materials published by Wiley-VCH GmbH This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.Science & TechnologyPhysical SciencesTechnologyChemistry, PhysicalEnergy & FuelsMaterials Science, MultidisciplinaryPhysics, AppliedPhysics, Condensed MatterChemistryMaterials SciencePhysicsferroceneheterojunction engineeringLiTFSIperovskitesspiro-OMeTADCHARGE-TRANSFERHOLE TRANSPORTHALIDE PEROVSKITEPERFORMANCE ENHANCEMENTION MIGRATIONDYELAYERSTABILITYELECTRONFILMS0303 Macromolecular and Materials Chemistry0912 Materials Engineering0915 Interdisciplinary EngineeringJournal Articlehttps://www.dx.doi.org/10.1002/aenm.202200666https://onlinelibrary.wiley.com/doi/10.1002/aenm.202200666