Photoluminescence and photoconductivity to assess maximum open-circuit voltage and carrier transport in hybrid perovskites and other photovoltaic materials (Conference Presentation)

2019 ◽  
Author(s):  
Hugh W. Hillhouse
Keyword(s):  
Carrier Transport ◽  
Open Circuit Voltage ◽  
Open Circuit ◽  
Photovoltaic Materials

scholarly journals Precise control over reduction potential of fulleropyrrolidines for organic photovoltaic materials

RSC Advances ◽  
2017 ◽  
Vol 7 (12) ◽  
pp. 7122-7129 ◽  
Author(s):  
M. Karakawa ◽  
T. Nagai ◽  
K. Adachi ◽  
Y. Ie ◽  
Y. Aso
Keyword(s):  
Methoxy Group ◽  
Reduction Potential ◽  
Open Circuit Voltage ◽  
Open Circuit ◽  
Organic Photovoltaic ◽  
Substitution Pattern ◽  
Precise Control ◽  
Photovoltaic Materials ◽  
Organic Photovoltaic Materials

A series of fulleropyrrolidines containing fluorine- and methoxy group were synthesized. The substitution pattern influenced the reduction potential of the fulleropyrrolidines and enabled precise control over an open circuit voltage of OPV cells.

scholarly journals Towards Quantitative Interpretation of Fourier-Transform Photocurrent Spectroscopy on Thin-Film Solar Cells

Coatings ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 820
Author(s):  
Jakub Holovský ◽  
Michael Stuckelberger ◽  
Tomáš Finsterle ◽  
Brianna Conrad ◽  
Amalraj Peter Amalathas ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Solar Cells ◽  
Carrier Transport ◽  
Open Circuit Voltage ◽  
Defect Density ◽  
Open Circuit ◽  
Absorption Enhancement ◽  
Thickness Variation ◽  
Accurate Analysis ◽  
Photocurrent Spectroscopy

The method of detecting deep defects in photovoltaic materials by Fourier-Transform Photocurrent Spectroscopy has gone through continuous development during the last two decades. Still, giving quantitative predictions of photovoltaic device performance is a challenging task. As new materials appear, a prediction of potentially achievable open-circuit voltage with respect to bandgap is highly desirable. From thermodynamics, a prediction can be made based on the radiative limit, neglecting non-radiative recombination and carrier transport effects. Beyond this, more accurate analysis has to be done. First, the absolute defect density has to be calculated, taking into account optical effects, such as absorption enhancement, due to scattering. Secondly, the electrical effect of thickness variation has to be addressed. We analyzed a series of state-of-the-art hydrogenated amorphous silicon solar cells of different thicknesses at different states of light soaking degradation. Based on a combination of empirical results with optical, electrical and thermodynamic simulations, we provide a predictive model of the open-circuit voltage of a device with a given defect density and absorber thickness. We observed that, rather than the defect density or thickness alone, it is their product or the total number of defects, that matters. Alternatively, including defect absorption into the thermodynamic radiative limit gives close upper bounds to the open-circuit voltage with the advantage of a much easier evaluation.

Design of organic small molecules for photovoltaic application with high open-circuit voltage (Voc)

2019 ◽  
Vol 7 (9) ◽  
pp. 2487-2521 ◽  
Author(s):  
Xiaodong He ◽  
Lunxiang Yin ◽  
Yanqin Li
Keyword(s):  
Small Molecules ◽  
Open Circuit Voltage ◽  
Molecular Design ◽  
Open Circuit ◽  
Efficient Approach ◽  
Photovoltaic Application ◽  
Photovoltaic Materials

An efficient approach to improve Voc values for OSCs through molecular design and modification of photovoltaic materials was summarized and discussed.

scholarly journals Investigation on the Overshoot of Transient Open-Circuit Voltage in Methylammonium Lead Iodide Perovskite Solar Cells

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2407
Author(s):  
Chunhai Li ◽  
Longfeng Lv ◽  
Liang Qin ◽  
Lijie Zhu ◽  
Feng Teng ◽  
...  
Keyword(s):  
Solar Cells ◽  
Light Pulse ◽  
Carrier Transport ◽  
Open Circuit Voltage ◽  
Perovskite Solar Cells ◽  
Open Circuit ◽  
Lead Iodide ◽  
Band Bending ◽  
Overshoot Phenomenon ◽  
Methylammonium Lead Iodide

Although the performance of hybrid organic-inorganic perovskite solar cells (PSCs) is encouraging, the detailed working principles and mechanisms of PSCs remain to be further studied. In this work, an overshoot phenomenon of open-circuit voltage (Voc) was observed when the illumination light pulse was switched off. The evolution of the Voc overshoot was systematically investigated along with the intensity and the width of the light pulse, the background illumination, and pretreatment by different bias. Based on the experimental results, we could conclude that the Voc overshoot originated from carrier motion against carrier collection direction, which happened at the ionic-accumulation-induced band bending areas near the interfaces between the perovskite active layer and the two carrier transport layers. The investigation on the Voc overshoot can help us to better understand ionic migration, carrier accumulation, and recombination of PSCs under open-circuit conditions.

Recombination and Resistive Losses in Amorphous Silicon / Crystalline Silicon Heterojunction Solar Cells

2000 ◽  
Vol 609 ◽  
Author(s):  
Nils Jensen ◽  
Uwe Rau ◽  
Jürgen H. Werner
Keyword(s):  
Solar Cells ◽  
Carrier Transport ◽  
Fill Factor ◽  
Open Circuit Voltage ◽  
Crystalline Silicon ◽  
Internal Quantum Efficiency ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Open Circuit ◽  
Absorber Material

ABSTRACTThis contribution investigates the electronic properties of a-Si:H/c-Si solar cells and explains their electrical output parameters open circuit voltage, short circuit current, and fill factor. Our device analysis is based on measurements of the internal quantum efficiency, of current/voltage and capacitance/voltage curves. We find carrier recombination within the crystalline silicon absorber material to be responsible for the limitation of the open circuit voltage. The short circuit current is restricted by collection losses in the absorber material and by absorption in the electrically inactive a-Si:H emitter. Resistive losses affecting the fill factor originate from the transport of minority carriers across the interface. The I/V curves measured at low temperatures reveal a characteristic S-shaped behavior. This effect increases with decrasing temperature and stems from the minority carrier transport, which is hindered by the band offset between a-Si:H and c-Si. We propose a new analytical model to describe this anomalous behavior.

Spontaneous open-circuit voltage gain of fully fabricated organic solar cells caused by elimination of interfacial energy disorder

2019 ◽  
Vol 12 (8) ◽  
pp. 2518-2528 ◽  
Author(s):  
Rui Sun ◽  
Dan Deng ◽  
Jing Guo ◽  
Qiang Wu ◽  
Jie Guo ◽  
...  
Keyword(s):  
Solar Cells ◽  
Surface Energy ◽  
Interfacial Energy ◽  
Organic Solar Cells ◽  
Open Circuit Voltage ◽  
Open Circuit ◽  
Voltage Gain ◽  
Energy Parameters ◽  
Photovoltaic Materials ◽  
Energy Disorder

The investigation of the surface energy parameters of photovoltaic materials highlights the wetting coefficient as a dominant dynamic for spontaneous Voc gain.

scholarly journals Enhancing the Performance of Aqueous Solution-Processed Cu2ZnSn(S,Se)4 Photovoltaic Materials by Mn2+ Substitution

Nanomaterials ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 1250
Author(s):  
Wenjie He ◽  
Yingrui Sui ◽  
Fancong Zeng ◽  
Zhanwu Wang ◽  
Fengyou Wang ◽  
...  
Keyword(s):  
Band Gap ◽  
Open Circuit Voltage ◽  
Power Conversion ◽  
Sol Gel ◽  
Open Circuit ◽  
Device Performance ◽  
Alloy Films ◽  
Photovoltaic Materials ◽  
Smooth Film ◽  
Mn Substitution

In this work, the Cu2MnxZn1−xSn(S,Se)4 (0 ≤ x ≤ 1) (CMZTSSe) alloy films were fabricated by a sol-gel method. Meanwhile, the effects of Mn substitution on the structural, morphological, electrical, optical, and device performance were studied systematically. The clear phase transformation from Cu2ZnSn(S,Se)4 (CZTSSe) with kesterite structure to Cu2MnSn(S,Se)4 (CMTSSe) with stannite structure was observed as x = 0.4. The scanning electron microscope (SEM) results show that the Mn can facilitate the grain growth of CMZTSSe alloy films. Since the x was 0.1, the uniform, compact, and smooth film was obtained. The results show that the band gap of the CMZTSSe film with a kesterite structure was incessantly increased in a scope of 1.024–1.054 eV with the increase of x from 0 to 0.3, and the band gap of the CMZTSSe film with stannite structure was incessantly decreased in a scope of 1.047–1.013 eV with the increase of x from 0.4 to 1. Meanwhile, compared to the power conversion efficiency (PCE) of pure CZTSSe device, the PCE of CMZTSSe (x = 0.1) device is improved from 3.61% to 4.90%, and about a maximum enhanced the open-circuit voltage (VOC) of 30 mV is achieved. The improvement is concerned with the enhancement of the grain size and decrease of the Cu instead of Zn (CuZn) anti-site defects. Therefore, it is believed that the adjunction of a small amount of Mn may be an appropriate approach to improve the PCE of CZTSSe solar cells.

Microcrystalline (Si,Ge):H Solar Cells

2003 ◽  
Vol 762 ◽  
Author(s):  
Jianhua Zhu ◽  
Vikram L. Dalal
Keyword(s):  
Solar Cells ◽  
Buffer Layer ◽  
Quantum Efficiency ◽  
Fill Factor ◽  
Open Circuit Voltage ◽  
Defect Density ◽  
Cell Structure ◽  
Open Circuit ◽  
Base Layer ◽  
Ecr Plasma

AbstractWe report on the growth and properties of microcrystalline Si:H and (Si,Ge):H solar cells on stainless steel substrates. The solar cells were grown using a remote, low pressure ECR plasma system. In order to crystallize (Si,Ge), much higher hydrogen dilution (∼40:1) had to be used compared to the case for mc-Si:H, where a dilution of 10:1 was adequate for crystallization. The solar cell structure was of the p+nn+ type, with light entering the p+ layer. It was found that it was advantageous to use a thin a-Si:H buffer layer at the back of the cells in order to reduce shunt density and improve the performance of the cells. A graded gap buffer layer was used at the p+n interface so as to improve the open-circuit voltage and fill factor. The open circuit voltage and fill factor decreased as the Ge content increased. Quantum efficiency measurements indicated that the device was indeed microcrystalline and followed the absorption characteristics of crystalline ( Si,Ge). As the Ge content increased, quantum efficiency in the infrared increased. X-ray measurements of films indicated grain sizes of ∼ 10nm. EDAX measurements were used to measure the Ge content in the films and devices. Capacitance measurements at low frequencies ( ~100 Hz and 1 kHz) indicated that the base layer was indeed behaving as a crystalline material, with classical C(V) curves. The defect density varied between 1x1016 to 2x1017/cm3, with higher defects indicated as the Ge concentration increased.

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