Interfacial and bulk properties of hole transporting materials in perovskite solar cells: spiro-MeTAD versus spiro-OMeTAD. Issue 17 (21st April 2020)

• Record Type: Journal Article
• Authors: Sallenave, Xavier; Shasti, Mona; Anaraki, Elham Halvani; Volyniuk, Dmytro; Grazulevicius, Juozas Vidas; Zakeeruddin, Shaik M.; Mortezaali, Abdollah; Grätzel, Michael; Hagfeldt, Anders; Sini, Gjergji
• Is Part Of: Journal of materials chemistry. Volume 8:Issue 17(2020)
• Page Start: 8527
• Page End: 8539
• Publication Date: 2020-04-21
• Subjects: Materials -- Research -- Periodicals; Chemistry, Analytic -- Periodicals; Environmental sciences -- Research -- Periodicals; 543.0284
• DOI: 10.1039/d0ta00623h
• Languages: English
• ISSNs: 2050-7488

Abstract

Abstract : Improving perovskite–HTM interface properties in solar cells is more important than just improving HTM hole mobility. Abstract : Two spiro-MeTAD compounds (1 and 2 ) were synthesized, characterized by experimental and quantum mechanical methods, and used as hole transporting materials (HTMs) in perovskite solar cells (PSCs). The new compounds differ from spiro-OMeTAD only by the presence of methyl substituents as compared to methoxy groups. This modification results in the absorption band blue shifting by ∼20 nm as compared to spiro-OMeTAD, increased glass transition temperature for 2, and reduced ionization potentials by 0.02–0.12 eV. Hole mobilities five times larger were obtained for spiro-MeTAD/spiro-MeTAD, which is maintained in the presence of additives. Despite this improvement, J – V measurements in PSCs resulted in a power conversion efficiency (PCE) of 17.2% and 17.05% for 1 and 2 HTMs, respectively, as compared to 19.24% for spiro-OMeTAD. Photoluminescence measurements of perovskite:HTM layers indicate much stronger quenching in the case of spiro-OMeTAD/spiro-MeTAD. These results point to the dominant importance of the perovskite:HTM interfacial properties as compared to the HTM hole-transport properties in the bulk. Given that improved hole-mobility and energy-level alignment are the main targets of the current research efforts in this domain, our results alert to the necessity to prioritize the improvement of perovskite–HTM interaction properties.