Influence of organic cations on high-performance CH sub(3)NH sub(3)PbI sub(3) based photovoltaics

A comprehensive study was carried out to understand the influence of organic cations on high-performance CH sub(3)NH sub(3)PbI sub(3) based photovoltaics. Scanning electron microscope, X-ray diffractometer, Hall measurement, absorbance spectrum, photoluminescence (PL) spectrum and nanosecond time-re...

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Bibliographic Details
Published in:Solar energy materials and solar cells 2016-02, Vol.145 (Part 3), p.375-381
Main Authors: Changa, Sheng Hsiung, Lina, Kuen-Feng, Chengc, Hsin-Ming, Chena, Cheng-Chiang, Wud, Wen-Ti, Chena, Wei-Nien, Wue, Pin-Jiun, Chenb, Sheng-Hui, Wua, Chun-Guey
Format: Article
Language:English
Subjects:
Absorbance
Annealing
Cations
Current density
Photovoltaic cells
Scanning electron microscopy
Solar cells
Thin films
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Summary:A comprehensive study was carried out to understand the influence of organic cations on high-performance CH sub(3)NH sub(3)PbI sub(3) based photovoltaics. Scanning electron microscope, X-ray diffractometer, Hall measurement, absorbance spectrum, photoluminescence (PL) spectrum and nanosecond time-resolved PL measurements were used to explore the structural, electrical, optical and excitonic characteristics of CH sub(3)NH sub(3)PbI sub(3) thin films fabricated under different thermal annealing temperatures from 60 degree C to 140 degree C. The decrease in the open-circuit voltage (V sub(OC)) with an increase in the thermal annealing temperature can be explained as due to the reduced work function of the CH sub(3)NH sub(3)PbI sub(3) thin film. The short-circuit current density (J sub(SC)) of the CH sub(3)NH sub(3)PbI sub(3) based photovoltaics is dependent on the efficiencies of light absorption and carrier collection, which results in an optimized J sub(SC) when the thermal annealing temperature is 120 degree C. The atomistic interaction between the organic cations and Pb-I framework strongly influences the absorbance of CH sub(3)NH sub(3)PbI sub(3) thin films, as confirmed by the libration of CH sub(3)NH sub(3) cations shown by Raman scattering spectroscopy. In addition, the experimental results indicate that the power conversion efficiency can be further improved when the absorption strength of the CH sub(3)NH sub(3)PbI sub(3) thin film and the energy-level alignment of each photovoltaic layer are simultaneously fulfilled.
ISSN:0927-0248
DOI:10.1016/j.solmat.2015.10.045