Volume 2, Issue 5, Pages 676-687 (May 2017) Tailor-Making Low-Cost Spiro[fluorene-9,9′-xanthene]-Based 3D Oligomers for Perovskite Solar Cells  Bo Xu, Jinbao Zhang, Yong Hua, Peng Liu, Linqin Wang, Changqing Ruan, Yuanyuan Li, Gerrit Boschloo, Erik M.J. Johansson, Lars Kloo, Anders Hagfeldt, Alex K.-Y. Jen, Licheng Sun  Chem  Volume 2, Issue 5, Pages 676-687 (May 2017) DOI: 10.1016/j.chempr.2017.03.011 Copyright © 2017 Elsevier Inc. Terms and Conditions

Chem 2017 2, 676-687DOI: (10.1016/j.chempr.2017.03.011) Copyright © 2017 Elsevier Inc. Terms and Conditions

Figure 1 Chemical Structure and Molecular Geometry of the HTMs (A) Chemical structures of the HTMs X54, X55, and Spiro-OMeTAD; the molecular weight is given in g/mol. (B) Simulated molecular geometry of X54 and X55. Chem 2017 2, 676-687DOI: (10.1016/j.chempr.2017.03.011) Copyright © 2017 Elsevier Inc. Terms and Conditions

Figure 2 Thermal and Photoelectrical Properties of the HTMs (A) Thermogravimetric analysis (TGA) of X54, X55, and Spiro-OMeTAD. (B) Differential scanning calorimetry results (DSC) of X54, X55, and Spiro-OMeTAD. (C) J-V characteristics of X54-, X55-, and Spiro-OMeTAD-based hole-only devices. (D) Current-voltage characteristics of X54-, X55-, and Spiro-OMeTAD-based solid films. Chem 2017 2, 676-687DOI: (10.1016/j.chempr.2017.03.011) Copyright © 2017 Elsevier Inc. Terms and Conditions

Figure 3 Photophysical and Electrochemical Properties of the HTMs (A) UV-vis absorption of X54, X55, and Spiro-OMeTAD solutions (10−5 M in toluene) upon stepwise addition of the p-type dopant FK209. (B) Cyclic voltammetry results of X54, X55, and Spiro-OMeTAD (10−4 M in dichloromethane). (C) Normalized differential pulsed voltammetry (DPV) results of X54, X55, and Spiro-OMeTAD (10−4 M in dichloromethane). (D) Device structure of the mesoscopic PSC used in this study. (E) Energy-level diagram of the related materials used in this study. Chem 2017 2, 676-687DOI: (10.1016/j.chempr.2017.03.011) Copyright © 2017 Elsevier Inc. Terms and Conditions

Figure 4 Photovoltaic Properties of the HTMs (A) J-V characteristics of the champion PSC devices using X54, X55, and Spiro-OMeTAD as the HTM obtained under 100 mW·cm−2 AM1.5G solar illumination. (B) Corresponding IPCE spectra of X54-, X55-, and Spiro-OMeTAD-based PSCs. (C) Stability of the photovoltaic parameters maintaining the PSCs at the maximum power point. (D) Statistical efficiencies for X54-, X55-, and Spiro-OMeTAD-based PSCs (at least 16 individual devices were studied). (E) J-V characteristics of Spiro-OMeTAD-based PSCs under different scan conditions after aging for 6 months. (F) J-V characteristics of X55-based PSCs under different scan conditions after aging for 6 months. Chem 2017 2, 676-687DOI: (10.1016/j.chempr.2017.03.011) Copyright © 2017 Elsevier Inc. Terms and Conditions

Figure 5 Morphology, Charge Transfer, and Transport Properties of the HTMs (A) Scanning electron microscopy (SEM) images of the HTM layer (top view). (B) Photoluminescence decay of perovskite films with and without HTMs in contact. (C) Normalized transient photocurrent decay under short-circuit conditions. Chem 2017 2, 676-687DOI: (10.1016/j.chempr.2017.03.011) Copyright © 2017 Elsevier Inc. Terms and Conditions

Scheme 1 The One-Pot Synthesis Approach of X55 Chem 2017 2, 676-687DOI: (10.1016/j.chempr.2017.03.011) Copyright © 2017 Elsevier Inc. Terms and Conditions