Scanning probe study on the photovoltaic characteristics of a Si solar cell by using Kelvin force microscopy and photoconductive atomic force microscopy

Heo, Jinhee; Won, Soonho

doi:10.1016/j.tsf.2013.04.076

Cited by 6 publications

(6 citation statements)

References 13 publications

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“…Before starting I-V and KPFM measurements, the impact of the AFM's LBBDS was investigated. Indeed, it has already been shown that the wavelength of the LBBDS can have a significant interaction with photovoltaic samples [8][9][10] and so may influence electrical properties measurements with the AFM. Figure 2 illustrates the macroscopic I-V measurements of a completed SiNW RJ device performed under dark conditions (LBBDS switched off) and when the LBBDS is kept on.…”

Section: Resultsmentioning

confidence: 99%

“…KPFM and SPV measurements were performed using a scanning probe microscopy system from HORIBA/AIST-NT (TRIOS platform) that offers several advantages. Indeed, for this atomic force microscope (AFM) the laser beam-based deflection system (LBBDS) employs a laser wavelength at 1310 nm that minimizes the possible photoelectric interactions with the sample [8][9][10]. This will be emphasized here by comparing data acquired using this platform with that obtained using an AFM system that uses a 690 nm wavelength for the LBBDS.…”

Section: Kelvin-probe and Surface Photovoltagementioning

confidence: 99%

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Local VOC Measurements by Kelvin Probe Force Microscopy Applied on P-I-N Radial Junction Si Nanowires

et al. 2019

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This work focuses on the extraction of the open circuit voltage (V OC) on photovoltaic nanowires by surface photovoltage (SPV) based on Kelvin probe force microscopy (KPFM) measurements. In a first approach, P-IN radial junction (RJ) silicon nanowire (SiNW) devices were investigated under illumination by KPFM and current-voltage (I-V) analysis. Within 5%, the extracted SPV correlates well with the V OC. In a second approach, local SPV measurements were applied on single isolated radial junction SiNWs pointing out shadowing effects from the AFM tip that can strongly impact the SPV assessment. Several strategies in terms of AFM tip shape and illumination orientation have been put in place to minimize this effect. Local SPV measurements on isolated radial junction SiNWs increase logarithmically with the illumination power and demonstrate a linear behavior with the V OC. The results show notably that contactless measurements of the V OC become feasible at the scale of single photovoltaic SiNW devices.

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Section: Resultsmentioning

confidence: 99%

Section: Kelvin-probe and Surface Photovoltagementioning

confidence: 99%

Local VOC Measurements by Kelvin Probe Force Microscopy Applied on P-I-N Radial Junction Si Nanowires

et al. 2019

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“…46 To investigate the CZTGS devices, KPFM measurements have been performed on the cross-section of the device. KPFM measurements were performed under ambient conditions using a scanning probe microscopy system from AIST-NT (TRIOS platform) 47 in two-pass scanning mode where the second pass was performed at a constant distance of 30 nm from the sample surface. To measure the surface potential, ARROW EFM conductive tips with a PtIr coating at a resonance frequency of 75 kHz were used.…”

Section: Acs Omegamentioning

confidence: 99%

Band-Gap Tuning Induced by Germanium Introduction in Solution-Processed Kesterite Thin Films

et al. 2022

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In the last few decades, the attention of scientific community has been driven toward the research on renewable energies. In particular, the photovoltaic (PV) thin-film technology has been widely explored to provide suitable candidates as top cells for tandem architectures, with the purpose of enhancing current PV efficiencies. One of the most studied absorbers, made of earth-abundant elements, is kesterite Cu 2 ZnSnS 4 (CZTS), showing a high absorption coefficient and a band gap around 1.4–1.5 eV. In particular, thanks to the ease of band-gap tuning by partial/total substitution of one or more of its elements, the high-band-gap kesterite derivatives have drawn a lot of attention aiming to find the perfect partner as a top absorber to couple with silicon in tandem solar cells (especially in a four-terminal architecture). In this work, we report the effects of the substitution of tin with different amounts of germanium in CZTS-based solar cells produced with an extremely simple sol–gel process, demonstrating how it is possible to fine-tune the band gap of the absorber and change its chemical–physical properties in this way. The precursor solution was directly drop-cast onto the substrate and spread with the aid of a film applicator, followed by a few minutes of gelation and annealing in an inert atmosphere. The desired crystalline phase was obtained without the aid of external sulfur sources as the precursor solution contained thiourea as well as metal acetates responsible for the in situ coordination and thus the correct networking of the metal centers. The addition of KCl in dopant amounts to the precursor solution allowed the formation of well-grown compact grains and enhanced the material quality. The materials obtained with the optimized procedure were characterized in depth through different techniques, and they showed very good properties in terms of purity, compactness, and grain size. Moreover, solar-cell prototypes were produced and measured, exhibiting poor charge extraction due to heavy back-contact sulfurization as studied in depth and experimentally demonstrated through Kelvin probe force microscopy.

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“…We find that the local variations in the V oc are due to the fact that different grain orientations can act as distinct centers for recombination within the material. Although KPFM measurements under illumination (named surface photovoltage—SPV) have been realized in a variety of solar cells technology, we demonstrate for the first time the direct correlation between SPV measurements (light minus dark KPFM) and the V oc of photovoltaic devices, through the measurement of the quasi‐Fermi level splitting. Our nanoscale metrology is nondestructive and can be implemented in ambient conditions, allowing for the diagnosis of how the different processing steps can affect the recombination within the material and, therefore, the ultimate performance of an optoelectronic device.…”

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confidence: 92%

Nanoimaging of Open‐Circuit Voltage in Photovoltaic Devices

Tennyson

Garrett

Frantz

et al. 2015

Advanced Energy Materials

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voltage and the overall electrical behavior of a device strongly depend on the nonradiative recombination rate of the charge carriers within a material, which is affected by the defects inherently present within the semiconductor. Despite all the efforts in developing higher performance thin-fi lm polycrystalline solar cells, such as CdTe, CuIn x Ga (1− x ) Se 2 (CIGS), and Cu 2 ZnSnS 4 (CZTS), the difference between the theoretically predicted and the best experimentally achieved V oc is still considerably large (up to 0.6 V). [ 2,3 ] For Si, extensive research has been dedicated to design and implement nanostructured light-trapping architectures to boost light absorption; [4][5][6][7] however, there are very few experiments showing how the V oc is affected. For organic PV blends, the limited V oc observed in most bulk heterojunction solar cells is attributed to geminate and nongeminate losses; [ 8,9 ] nevertheless, local variations in V oc have never been measured. Thus, for any micrometer-and nanoscale structured PV device, assessing variations in V oc with nanoscale resolution and spatially resolving where recombination occurs within the material can potentially change the pathway for designing higher performance devices.Imaging methods based on atomic force microscopy (AFM) techniques have been extensively used to characterize the structural and electrical properties of PV materials and full devices. [10][11][12][13][14][15][16][17][18][19][20][21] In particular, Kelvin probe force microscopy (KPFM) has been implemented to probe the electrical characteristics of a variety of PV materials and devices, ranging from organic materials [ 9,[22][23][24] and oxides [ 25 ] to III-V semiconductors for multijunction designs [26][27][28] and polycrystalline thin fi lms. [ 18,[29][30][31][32][33][34][35] The local optoelectronic properties and changes in material composition have also been mapped using near-fi eld scanning optical microscopy (NSOM) probes as local sources of excitation. [36][37][38][39][40][41][42] Very recently, photoluminescence has emerged as a promising tool to map charge recombination [43][44][45] and carriers diffusion [ 46 ] with high spatial resolution. At low temperature (70 K), photoluminescence imaging with submicrometer resolution has been implemented to map a 10 meV quasi-Fermi level splitting in CIGS solar cells, where variations in the intensity signal were attributed to changes in the material composition. [ 47 ] Nevertheless, none of these imaging techniques provide a direct measurement of V oc within the material at operating conditions. A straightforward, universal, and accurate method to measure the V oc (and hence nonradiative recombination processes) with high spatial resolution in PV materials is still missing.Here, we present a new imaging technique based on illuminated KPFM to map the V oc of optoelectronic devices with nanoscale resolution <100 nm. We map the contact potential difference (CPD) of half or fully processed solar cells in the For most photovoltaic (PV) devices, the...

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Scanning probe study on the photovoltaic characteristics of a Si solar cell by using Kelvin force microscopy and photoconductive atomic force microscopy

Cited by 6 publications

References 13 publications

Local VOC Measurements by Kelvin Probe Force Microscopy Applied on P-I-N Radial Junction Si Nanowires

Local VOC Measurements by Kelvin Probe Force Microscopy Applied on P-I-N Radial Junction Si Nanowires

Band-Gap Tuning Induced by Germanium Introduction in Solution-Processed Kesterite Thin Films

Nanoimaging of Open‐Circuit Voltage in Photovoltaic Devices

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