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Lead iodide perovskite light-emitting field-effect transistor.

Chin XY, Cortecchia D, Yin J, Bruno A, Soci C - Nat Commun (2015)

Bottom Line: Here we show that screening effects associated to ionic transport can be effectively eliminated by lowering the operating temperature of methylammonium lead iodide perovskite (CH3NH3PbI3) field-effect transistors.Field-effect carrier mobility is found to increase by almost two orders of magnitude below 200 K, consistent with phonon scattering-limited transport.This demonstration of CH3NH3PbI3 light-emitting field-effect transistors provides intrinsic transport parameters to guide materials and solar cell optimization, and will drive the development of new electro-optic device concepts, such as gated light-emitting diodes and lasers operating at room temperature.

View Article: PubMed Central - PubMed

Affiliation: Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore.

ABSTRACT
Despite the widespread use of solution-processable hybrid organic-inorganic perovskites in photovoltaic and light-emitting applications, determination of their intrinsic charge transport parameters has been elusive due to the variability of film preparation and history-dependent device performance. Here we show that screening effects associated to ionic transport can be effectively eliminated by lowering the operating temperature of methylammonium lead iodide perovskite (CH3NH3PbI3) field-effect transistors. Field-effect carrier mobility is found to increase by almost two orders of magnitude below 200 K, consistent with phonon scattering-limited transport. Under balanced ambipolar carrier injection, gate-dependent electroluminescence is also observed from the transistor channel, with spectra revealing the tetragonal to orthorhombic phase transition. This demonstration of CH3NH3PbI3 light-emitting field-effect transistors provides intrinsic transport parameters to guide materials and solar cell optimization, and will drive the development of new electro-optic device concepts, such as gated light-emitting diodes and lasers operating at room temperature.

No MeSH data available.


Low-temperature electroluminescence spectra of CH3NH3PbI3 LE-FET.EL spectra collected at Vds=100 V, Vgs=100 V, normalized to their maximum peak. The spectra were fitted by three Gaussian curves (solid lines). The shift in peak position of the 750 nm peak (Peak 1, blue triangles), the 780 nm peak (Peak 2, red circles) and the 800 nm peak (Peak 3, black squares) is indicated by the dashed lines.
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f4: Low-temperature electroluminescence spectra of CH3NH3PbI3 LE-FET.EL spectra collected at Vds=100 V, Vgs=100 V, normalized to their maximum peak. The spectra were fitted by three Gaussian curves (solid lines). The shift in peak position of the 750 nm peak (Peak 1, blue triangles), the 780 nm peak (Peak 2, red circles) and the 800 nm peak (Peak 3, black squares) is indicated by the dashed lines.

Mentions: Indeed, our CH3NH3PbI3 FETs emit light when operated in their ambipolar regime at low temperature (78–178 K). Typical EL spectra are displayed in Fig. 4. Note that no light emission could be observed above 198 K, most likely due to the ionic screening effects discussed earlier, so that low-temperature operation is necessary at this stage. Ionic screening is likely to be reduced in films with higher crystallinity as those recently reported3031, potentially enabling perovskite LE-FET operation up to room temperature. The emission spectra of the LE-FET are consistent with direct recombination of injected electrons and holes into the perovskite-active region. At the lowest temperature investigated (78 K), the EL spectrum shows three peaks centred at 750 nm (Peak 1), 780 nm (Peak 2) and 800 nm (Peak 3), with distinct amplitudes and spectral positions at the various temperatures. Although Peak 1 and Peak 3 appear only below 158 K, Peak 2 dominates the EL spectra at higher temperatures. A similar behaviour was very recently observed in photoluminescence spectra of CH3NH3PbI3 films and single crystals5859, and related to the structural transition from a low-temperature orthorhombic phase to a high-temperature tetragonal phase occurring around 162 K. Occurrence of this phase transition is predicted by density functional theory6061 (see also DFT calculations in Fig. 3c,d) and was confirmed to occur in the temperature ranges of 150–170 K for CH3NH3PbI3 and 120–140 K for hybrid CH3NH3PbI3−xClx by light absorption studies6. Thus, their characteristic temperature dependence suggests that Peak 1 and Peak 3 in our EL measurements are due to bound excitons in the low-temperature orthorhombic phase, whereas Peak 2 may be related to free excitons in the high temperature, smaller bandgap tetragonal phase59. To quantify the relative intensity and spectral energy of the three emission peaks as a function of temperature, we analysed the EL spectra by a deconvoluted Gaussian fitting (see Gaussian curves in Fig. 4 and corresponding fitted parameters in Supplementary Fig. 5). Although Peak 1 shows the expected blue shift at the lowest temperatures, its temperature dependence in the intermediate range 118–178 K is rather complicated (Supplementary Fig. 5a). Peak 2 position slightly blue shifts over the whole temperature region, whereas Peak 3 shows a significant red shift in the 138–78 K region. Moreover, although the Gaussian full-width at half-maximum of Peak 1 reduces at lower temperatures, the full-width at half-maximum of Peak 2 and Peak 3 shows the opposite behaviour (Supplementary Fig. 5b), as previously seen in low-temperature photoluminescence measurements5859. At this stage, the anomalous spectral shift and broadening of the EL peaks and the nature of the three peaks as a function of temperature are not completely understood, and further investigations are needed to reveal their nature.


Lead iodide perovskite light-emitting field-effect transistor.

Chin XY, Cortecchia D, Yin J, Bruno A, Soci C - Nat Commun (2015)

Low-temperature electroluminescence spectra of CH3NH3PbI3 LE-FET.EL spectra collected at Vds=100 V, Vgs=100 V, normalized to their maximum peak. The spectra were fitted by three Gaussian curves (solid lines). The shift in peak position of the 750 nm peak (Peak 1, blue triangles), the 780 nm peak (Peak 2, red circles) and the 800 nm peak (Peak 3, black squares) is indicated by the dashed lines.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4491174&req=5

f4: Low-temperature electroluminescence spectra of CH3NH3PbI3 LE-FET.EL spectra collected at Vds=100 V, Vgs=100 V, normalized to their maximum peak. The spectra were fitted by three Gaussian curves (solid lines). The shift in peak position of the 750 nm peak (Peak 1, blue triangles), the 780 nm peak (Peak 2, red circles) and the 800 nm peak (Peak 3, black squares) is indicated by the dashed lines.
Mentions: Indeed, our CH3NH3PbI3 FETs emit light when operated in their ambipolar regime at low temperature (78–178 K). Typical EL spectra are displayed in Fig. 4. Note that no light emission could be observed above 198 K, most likely due to the ionic screening effects discussed earlier, so that low-temperature operation is necessary at this stage. Ionic screening is likely to be reduced in films with higher crystallinity as those recently reported3031, potentially enabling perovskite LE-FET operation up to room temperature. The emission spectra of the LE-FET are consistent with direct recombination of injected electrons and holes into the perovskite-active region. At the lowest temperature investigated (78 K), the EL spectrum shows three peaks centred at 750 nm (Peak 1), 780 nm (Peak 2) and 800 nm (Peak 3), with distinct amplitudes and spectral positions at the various temperatures. Although Peak 1 and Peak 3 appear only below 158 K, Peak 2 dominates the EL spectra at higher temperatures. A similar behaviour was very recently observed in photoluminescence spectra of CH3NH3PbI3 films and single crystals5859, and related to the structural transition from a low-temperature orthorhombic phase to a high-temperature tetragonal phase occurring around 162 K. Occurrence of this phase transition is predicted by density functional theory6061 (see also DFT calculations in Fig. 3c,d) and was confirmed to occur in the temperature ranges of 150–170 K for CH3NH3PbI3 and 120–140 K for hybrid CH3NH3PbI3−xClx by light absorption studies6. Thus, their characteristic temperature dependence suggests that Peak 1 and Peak 3 in our EL measurements are due to bound excitons in the low-temperature orthorhombic phase, whereas Peak 2 may be related to free excitons in the high temperature, smaller bandgap tetragonal phase59. To quantify the relative intensity and spectral energy of the three emission peaks as a function of temperature, we analysed the EL spectra by a deconvoluted Gaussian fitting (see Gaussian curves in Fig. 4 and corresponding fitted parameters in Supplementary Fig. 5). Although Peak 1 shows the expected blue shift at the lowest temperatures, its temperature dependence in the intermediate range 118–178 K is rather complicated (Supplementary Fig. 5a). Peak 2 position slightly blue shifts over the whole temperature region, whereas Peak 3 shows a significant red shift in the 138–78 K region. Moreover, although the Gaussian full-width at half-maximum of Peak 1 reduces at lower temperatures, the full-width at half-maximum of Peak 2 and Peak 3 shows the opposite behaviour (Supplementary Fig. 5b), as previously seen in low-temperature photoluminescence measurements5859. At this stage, the anomalous spectral shift and broadening of the EL peaks and the nature of the three peaks as a function of temperature are not completely understood, and further investigations are needed to reveal their nature.

Bottom Line: Here we show that screening effects associated to ionic transport can be effectively eliminated by lowering the operating temperature of methylammonium lead iodide perovskite (CH3NH3PbI3) field-effect transistors.Field-effect carrier mobility is found to increase by almost two orders of magnitude below 200 K, consistent with phonon scattering-limited transport.This demonstration of CH3NH3PbI3 light-emitting field-effect transistors provides intrinsic transport parameters to guide materials and solar cell optimization, and will drive the development of new electro-optic device concepts, such as gated light-emitting diodes and lasers operating at room temperature.

View Article: PubMed Central - PubMed

Affiliation: Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore.

ABSTRACT
Despite the widespread use of solution-processable hybrid organic-inorganic perovskites in photovoltaic and light-emitting applications, determination of their intrinsic charge transport parameters has been elusive due to the variability of film preparation and history-dependent device performance. Here we show that screening effects associated to ionic transport can be effectively eliminated by lowering the operating temperature of methylammonium lead iodide perovskite (CH3NH3PbI3) field-effect transistors. Field-effect carrier mobility is found to increase by almost two orders of magnitude below 200 K, consistent with phonon scattering-limited transport. Under balanced ambipolar carrier injection, gate-dependent electroluminescence is also observed from the transistor channel, with spectra revealing the tetragonal to orthorhombic phase transition. This demonstration of CH3NH3PbI3 light-emitting field-effect transistors provides intrinsic transport parameters to guide materials and solar cell optimization, and will drive the development of new electro-optic device concepts, such as gated light-emitting diodes and lasers operating at room temperature.

No MeSH data available.