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Title: Remnant PbI2, an unforeseen necessity in high-efficiency hybrid perovskite-based solar cells?a)

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
Energy Frontier Research Centers (EFRC); Argonne-Northwestern Solar Energy Research Center (ANSER)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1210309
DOE Contract Number:
SC0001059
Resource Type:
Journal Article
Resource Relation:
Journal Name: APL Materials; Journal Volume: 2; Related Information: ANSER partners with Northwestern University (lead); Argonne National Laboratory; University of Chicago; University of Illinois, Urbana-Champaign; Yale University
Country of Publication:
United States
Language:
English
Subject:
catalysis (homogeneous), catalysis (heterogeneous), solar (photovoltaic), solar (fuels), photosynthesis (natural and artificial), bio-inspired, hydrogen and fuel cells, electrodes - solar, defects, charge transport, spin dynamics, membrane, materials and chemistry by design, optics, synthesis (novel materials), synthesis (self-assembly)

Citation Formats

Cao, Duyen H., Stoumpos, Constantinos C., Malliakas, Christos D., Katz, Michael J., Farha, Omar K., Hupp, Joseph T., and Kanatzidis, Mercouri G.. Remnant PbI2, an unforeseen necessity in high-efficiency hybrid perovskite-based solar cells?a). United States: N. p., 2014. Web. doi:10.1063/1.4895038.
Cao, Duyen H., Stoumpos, Constantinos C., Malliakas, Christos D., Katz, Michael J., Farha, Omar K., Hupp, Joseph T., & Kanatzidis, Mercouri G.. Remnant PbI2, an unforeseen necessity in high-efficiency hybrid perovskite-based solar cells?a). United States. doi:10.1063/1.4895038.
Cao, Duyen H., Stoumpos, Constantinos C., Malliakas, Christos D., Katz, Michael J., Farha, Omar K., Hupp, Joseph T., and Kanatzidis, Mercouri G.. Mon . "Remnant PbI2, an unforeseen necessity in high-efficiency hybrid perovskite-based solar cells?a)". United States. doi:10.1063/1.4895038.
@article{osti_1210309,
title = {Remnant PbI2, an unforeseen necessity in high-efficiency hybrid perovskite-based solar cells?a)},
author = {Cao, Duyen H. and Stoumpos, Constantinos C. and Malliakas, Christos D. and Katz, Michael J. and Farha, Omar K. and Hupp, Joseph T. and Kanatzidis, Mercouri G.},
abstractNote = {},
doi = {10.1063/1.4895038},
journal = {APL Materials},
number = ,
volume = 2,
place = {United States},
year = {Mon Sep 01 00:00:00 EDT 2014},
month = {Mon Sep 01 00:00:00 EDT 2014}
}
  • Perovskite-containing solar cells were fabricated in a two-step procedure in which PbI{sub 2} is deposited via spin-coating and subsequently converted to the CH{sub 3}NH{sub 3}PbI{sub 3} perovskite by dipping in a solution of CH{sub 3}NH{sub 3}I. By varying the dipping time from 5 s to 2 h, we observe that the device performance shows an unexpectedly remarkable trend. At dipping times below 15 min the current density and voltage of the device are enhanced from 10.1 mA/cm{sup 2} and 933 mV (5 s) to 15.1 mA/cm{sup 2} and 1036 mV (15 min). However, upon further conversion, the current density decreasesmore » to 9.7 mA/cm{sup 2} and 846 mV after 2 h. Based on X-ray diffraction data, we determined that remnant PbI{sub 2} is always present in these devices. Work function and dark current measurements showed that the remnant PbI{sub 2} has a beneficial effect and acts as a blocking layer between the TiO{sub 2} semiconductor and the perovskite itself reducing the probability of back electron transfer (charge recombination). Furthermore, we find that increased dipping time leads to an increase in the size of perovskite crystals at the perovskite-hole-transporting material interface. Overall, approximately 15 min dipping time (∼2% unconverted PbI{sub 2}) is necessary for achieving optimal device efficiency.« less
  • Hybrid perovskites represent a potential paradigm shift for the creation of low-cost solar cells. Current power conversion efficiencies (PCEs) exceed 22%. However, despite this, record PCEs are still far from their theoretical Shockley–Queisser limit of 31%. To increase these PCE values, there is a pressing need to understand, quantify and microscopically model charge recombination processes in full working devices. Here, we present a complete microscopic account of charge recombination processes in high efficiency (18–19% PCE) hybrid perovskite (mixed cation and methylammonium lead iodide) solar cells. We employ diffraction-limited optical measurements along with relevant kinetic modeling to establish, for the firstmore » time, local photoluminescence quantum yields, trap densities, trapping efficiencies, charge extraction efficiencies, quasi-Fermi-level splitting, and effective PCE estimates. Correlations between these spatially resolved parameters, in turn, allow us to conclude that intrinsic electron traps in the perovskite active layers limit the performance of these state-of-the-art hybrid perovskite solar cells.« less
  • High-performance planar heterojunction perovskite (CH3NH3PbI3) solar cell (PVSC) is demonstrated by utilizing CuSCN as a hole-transporting layer. Efficient hole-transport and hole-extraction at the CuSCN/CH3NH3PbI3 interface facilitate the PVSCs to reach 16% power conversion efficiency (PCE). In addition, excellent transparency of CuSCN enables high-performance semitransparent PVSC (10% PCE and 25% average visible transmittance) to be realized.
  • The microstructure of the solid-PbI2 precursor thin film plays an important role in the intercalation crystallization of the formamidinium lead triiodide perovskite (..alpa..-HC(NH2)2PbI3). It is shown that microstructurally engineered PbI2 thin films with porosity and low crystallinity are the most favorable for conversion into uniform-coverage, phase-pure ..alpha..-HC(NH2)2PbI3 perovskite thin films. Planar perovskite solar cells fabricated using these thin films deliver power conversion efficiency (PCE) up to 13.8%.