Replication Data for: Role of Water in Suppressing Recombination Pathways in CH3NH3PbI3 Perovskite Solar Cells (doi:10.21979/N9/WUEMZC)

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Replication Data for: Role of Water in Suppressing Recombination Pathways in CH3NH3PbI3 Perovskite Solar Cells

doi:10.21979/N9/WUEMZC

DR-NTU (Data)

2020-04-17

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Ankur, Solanki; Lim Swee Sien; Subodh Mhaisalkar; Sum, Tze Chien, 2020, "Replication Data for: Role of Water in Suppressing Recombination Pathways in CH3NH3PbI3 Perovskite Solar Cells", https://doi.org/10.21979/N9/WUEMZC, DR-NTU (Data), V1

Replication Data for: Role of Water in Suppressing Recombination Pathways in CH3NH3PbI3 Perovskite Solar Cells

doi:10.21979/N9/WUEMZC

Ankur, Solanki (Nanyang Technological University)

Lim Swee Sien (Nanyang Technological University)

Subodh Mhaisalkar (Nanyang Technological University)

Sum, Tze Chien (Nanyang Technological University)

OriginLab

Microsoft Excel

start-up grant M4080514

AcRF Tier 2 grant MOE2016-T2-1-034

ONRGNICOP-N62909-17-1-2155

NRF2018-ITC001- 001

NRF-NRFI-2018-04

DR-NTU (Data)

Sum Tze Chien

Ankur Solanki

Ankur, Solanki

2020-04-16

https://doi.org/10.21979/N9/WUEMZC

Physics, Physics, Perovskite solar cells, charge carrier dynamics, recombination, water

Moisture degradation of halide perovskites is the Achilles heel of perovskite solar cells. A surprising revelation in 2014 about the beneficial effects of controlled humidity in enhancing device efficiencies overthrew established paradigms on perovskite solar cell fabrication. Despite the extensive studies on water additives in perovskite solar cell processing that followed, detailed understanding of the role of water from the photophysical perspective remains lacking; specifically, the interplay between the induced morphological effects and the intrinsic recombination pathways. Through ultrafast optical spectroscopy, we show that both the monomolecular and bimolecular recombination rate constants decrease by approximately 1 order with the addition of an optimal 1% H2O by volume in CH3NH3PbI3 as compared to the reference (without the H2O additive). Correspondingly, the trap density reduces from 4.8 × 1017 cm–3 (reference) to 3.2 × 1017 cm–3 with 1% H2O. We obtained an efficiency of 12.3% for the champion inverted CH3NH3PbI3 perovskite solar cell (1% H2O additive) as compared to the 10% efficiency for the reference cell. Increasing the H2O content further is deleterious for the device. Trace amounts of H2O afford the benefits of surface trap passivation and suppression of trap-mediated recombination, whereas higher concentrations result in a preferential dissolution of methylammonium iodide during fabrication that increases the trap density (MA vacancies). Importantly, our study reveals the effects of trace H2O additives on the photophysical properties of CH3NH3PbI3 films. DOI: 10.1021/acsami.9b00793

Experimental and modelling

DOI: 10.1021/acsami.9b00793

Solanki, A., Lim, S. S., Mhaisalkar, S., & Sum, T. C. (2019). Role of water in suppressing recombination pathways in CH3NH3PbI3 perovskite solar cells. ACS applied materials & interfaces, 11(28), 25474-25482.

10356/138050

Solanki, A., Lim, S. S., Mhaisalkar, S., & Sum, T. C. (2019). Role of water in suppressing pecombination pathways in CH3NH3PbI3 perovskite solar cells. ACS Applied Materials and Interfaces, 11(28), 25474-25482

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Cross-sectional SEM images of perovskite films with (a) 0, (b) 1 % H2O additive concentration coated on the PEDOT:PSS/ITO/glass substrate. (c,d) Corresponding morphology images across a 2 μm × 2 μm scanned area by AFM, where the RMS roughness is measured to be 4.9 and 4.4 nm for the 0 and 1 % H2O-added perovskite films, respectively. (e) Absorption spectra of various perovskite films, with an increase in absorbance in the shorter wavelengths (<500 nm). (f) Graphical representation of the variation of fwhm of the (110) XRD peak with various H2O concentrations.

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Characterization results from ultrafast optical spectroscopy detailing the recombination dynamics in the perovskite samples. (a) Calculation of trap density by plotting the measured integrated PL intensity against the photoexcited carrier density. (b) TRPL kinetic traces of the samples in the low-fluence regime, showing the superiority of 1% H2O additive. (c) Amplitude of lifetime components obtained from the fitting of power-dependent TRPL kinetics. (d) Recombination rates obtained by fitting the recombination rate equation (eq 1), with an estimated error of 10%.

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. (a) Electron (square) and hole (cross) diffusion lengths of the various samples with the respective quencher measured at a fluence of 0.5 μJ cm−2 and calculated with a 1D diffusion model (Figure S7 shows the fitting of TRPL data for different perovskite films). PC61BM is used as the electron quencher in a bilayer architecture to estimate the electron diffusion length, and PEDOT:PSS is used as the hole quencher. Modeling the diffusion lengths as a function of carrier density using eq 2 (b) with a PCBM electron quencher and (c) PEDOT:PSS hole quencher. Solid lines denote the results assuming k3 = 0, as this term is not required when fitting the power-dependent transients. Dashed lines denote the results assuming k3 = 10−28 cm6 s−1, a value typical of perovskite solar cells.

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(a) Schematic of the inverted device architecture used for the devices, (b) current density−voltage curves of the various additive concentrations: 0 % H2O control film, and 0.5, 1, 2 %, and 5 % H2O. (c) Champion cell performance with an additive concentration of 1 % H2O and hysteresis. (d) Statistical PCE data based on 25 devices.

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