Imperial College London


Faculty of Natural SciencesDepartment of Physics

Visiting Professor



+44 (0)20 7594 6669thomas.anthopoulos Website




Mrs Carolyn Dale +44 (0)20 7594 7579




1111Blackett LaboratorySouth Kensington Campus






BibTex format

author = {Barrit, D and Cheng, P and Tang, MC and Wang, K and Dang, H and Smilgies, DM and Liu, S and Anthopoulos, TD and Zhao, K and Amassian, A},
doi = {10.1002/adfm.201807544},
journal = {Advanced Functional Materials},
title = {Impact of the Solvation State of Lead Iodide on Its Two-Step Conversion to MAPbI <inf>3</inf> : An In Situ Investigation},
url = {},
year = {2019}

RIS format (EndNote, RefMan)

AB - © 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Producing high efficiency solar cells without high-temperature processing or use of additives still remains a challenge with the two-step process. Here, the solution processing of MAPbI 3 from PbI 2 films in N,N-dimethylformamide (DMF) is investigated. In-situ grazing incidence wide-angle X-ray scattering (GIWAXS) measurements reveal a sol–gel process involving three PbI 2 -DMF solvate complexes—disordered (P 0 ) and ordered (P 1 , P 2 )—prior to PbI 2 formation. When the appropriate solvated state of PbI 2 is exposed to MAI (methylammonium Iodide), it can lead to rapid and complete room temperature conversion into MAPbI 3 with higher quality films and improved solar cell performance. Complementary in-situ optical reflectance, absorbance, and quartz crystal microbalance with dissipation (QCM-D) measurements show that dry PbI 2 can take up only one third of the MAI taken up by the solvated-crystalline P 2 phase of PbI 2 , requiring additional annealing and yet still underperforming. The perovskite solar cells fabricated from the ordered P 2 precursor show higher power conversion efficiency (PCE) and reproducibility than devices fabricated from other cases. The average PCE of the solar cells is greatly improved from 13.2(±0.53)% (from annealed PbI 2 ) to 15.7(±0.35)% (from P 2 ) reaching up to 16.2%. This work demonstrates the importance of controlling the solvation of PbI 2 as an effective strategy for the growth of high-quality perovskite films and their application in high efficiency and reproducible solar cells.
AU - Barrit,D
AU - Cheng,P
AU - Tang,MC
AU - Wang,K
AU - Dang,H
AU - Smilgies,DM
AU - Liu,S
AU - Anthopoulos,TD
AU - Zhao,K
AU - Amassian,A
DO - 10.1002/adfm.201807544
PY - 2019///
SN - 1616-301X
TI - Impact of the Solvation State of Lead Iodide on Its Two-Step Conversion to MAPbI <inf>3</inf> : An In Situ Investigation
T2 - Advanced Functional Materials
UR -
ER -