An automated steady state photocarrier grating experiment

Longeaud, Christophe

doi:10.1063/1.4803006

Cited by 12 publications

(14 citation statements)

References 6 publications

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“…As mentioned above we have developed a bench on which SSPG can be performed automatically [19]. With this bench we can vary the grating period from 1 µm to 24 µm in 9 different steps, a range large enough for the studied samples.…”

Section: Resultsmentioning

confidence: 99%

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Determination of diffusion lengths in organic semiconductors: Correlation with solar cell performances

Longeaud

Allah

Schmidt

et al. 2016

Organic Electronics

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Organic semiconductors are promising candidates for future applications in solar energy conversion.Recent investigations of bulk heterojunction (BHJ) semiconductors have suggested a density of states and transport mechanisms by multiple trapping close to those observed in disordered inorganic thin films. That is why we have applied to BHJ thin films experiments that are currently used for disordered semiconductors. In addition to the steady state photoconductivity we have tested the ability of the steady state photocarrier grating (SSPG) technique to provide information on the minority carrier diffusion length. We found that SSPG can be applied to P3HT:PCBM thin films leading, for the best sample, to a diffusion length of the order of 125 nm. From the comparison of the transport parameters obtained on thin films with the performances of the devices integrating the latter, we conclude that SSPG is a very powerful tool for optimizing the BHJ thin film properties before their incorporation in solar devices.

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Section: Resultsmentioning

confidence: 99%

“…We have recently built a bench on which SSPC and SSPG measurements can be performed automatically [19] the sample being maintained under vacuum. The light illuminating the film is emitted by a He-Ne laser (633 nm).…”

Section: Characterisationsmentioning

confidence: 99%

Determination of diffusion lengths in organic semiconductors: Correlation with solar cell performances

Longeaud

Allah

Schmidt

et al. 2016

Organic Electronics

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“…Therefore, L amb as measured by SSPG, are influenced by the transport properties of the holes. Details of the experimental methods can be found elsewhere [25,26]. Figure 6 depicts the Balberg plots of the deposited film at various process pressures and estimated values of L amb and μτ are shown in Table 2.…”

Section: Transport Propertymentioning

confidence: 99%

Effect of Pressure on Bonding Environment and Carrier Transport of a-Si:H Thin Films Deposited Using 27.12 MHz Assisted PECVD Process

Chaudhary

Sharma

Sudhakar

et al. 2016

Silicon

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Investigation of carrier transport in hydrogenated amorphous silicon (a-Si:H) thin films deposited at various pressures (0.03 -0.53 Torr) using 27.12 MHz assisted high frequency Plasma Enhanced Chemical vapor Deposition (PECVD) process is presented. From results of Steady State Photocarrier Grating (SSPG) the carrier diffusion length was found to vary from 0.098 -0.189 μm. Moreover a direct influence of ambipolar diffusion length was observed with the transport mechanism for deposition pressure in the range (0.13 -0.53 Torr). There was a correlation observed for photosensitivity and microstructure parameter with mobility lifetime (μτ ) product and diffusion length of carriers. Diffusion length and μτ product were observed to be maximum (0.189 μm and 0.471 x 10 −8 cm 2 V −1 ) for the film having high photosensitivity (7.2x10 3 ) deposited at a rate ∼1.39Å/s at 0.53 Torr deposition pressure. In addition to electrical transport properties, the effect of deposition pressure on structural and optical properties was also studied using various characterization tools such as Raman, UV-Vis and infrared spectroscopy.

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“…To study the transport properties of these samples we have used the Steady State Photo Conductivity (SSPC) technique and the Steady States Photocarrier Grating (SSPG) technique [2]. This last technique has been largely improved to automatically perform measurements within a few minutes [3] to follow the fast evolution of the ambipolar diffusion length when experimental conditions, e.g. samples in air or under vacuum, are modified.…”

Section: Introductionmentioning

confidence: 99%

Study of transport parameters and defect states in thin film perovskites under different environments − air or vacuum − and after light-soaking

Longeaud

2020

EPJ Photovolt.

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We present some advanced characterization techniques developed to investigate on the opto-electronic properties of thin film semiconductors and apply them to perovskite layers. These techniques are the steady state photocarrier grating (SSPG) and the Fourier transform photocurrent spectroscopy (FTPS). The SSPG was developed to study the ambipolar diffusion length of carriers and the FTPS was imagined to measure the variations of the below gap absorption coefficient with the light energy, giving information on the defect densities of the gap responsible for this absorption. The potentialities of these techniques are first detailed and then exemplified by their application to thin film perovskites. To study their stability, these films were exposed to different environments, air or vacuum, and in their as-deposited state or after light-soaking with heavy light. We find that the diffusion length and density of states are quite stable, even after light-soaking, and suggest that the degradation of devices exposed to 1 sun mainly comes from the evolution of the contacts instead of the perovkite itself.

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An automated steady state photocarrier grating experiment

Cited by 12 publications

References 6 publications

Determination of diffusion lengths in organic semiconductors: Correlation with solar cell performances

Determination of diffusion lengths in organic semiconductors: Correlation with solar cell performances

Effect of Pressure on Bonding Environment and Carrier Transport of a-Si:H Thin Films Deposited Using 27.12 MHz Assisted PECVD Process

Study of transport parameters and defect states in thin film perovskites under different environments − air or vacuum − and after light-soaking

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