- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Effect of Precursor Aging on Builta??In Potential in Formamidiniuma??Based Perovskite Solar Cells
摘要： Formamidinium-based perovskite with optimal bandgap and improved thermal stability is a promising active material for application in perovskite solar cells (PSCs). The hybrid precursor solutions, formed by adding various smaller cations, are often used for improving the phase stability in PSCs. In this work, we report the effort on understanding the aging effect of a methylammonium- and bromine-free formamidinium precursor solution on the performance of FA0.85Cs0.1Rb0.05PbI3-based PSCs. Our results reveal that deterioration in the built-in potential in the PSCs is closely associated with the formation of the secondary phase in the FA0.85Cs0.1Rb0.05PbI3 active layer. The formation of the secondary phase in the active layer is related to the hydrolysis of the precursor solution. The suppression of the moisture encroachment greatly enhances the durability of the precursor solution and performance reproducibility of the PSCs.
关键词： precursor solution aging,perovskite solar cell,secondary phase,built-in potential
更新于2025-09-23 15:21:01
-
Interface Engineering Assisted 3D-Graphene/Germanium Heterojunction for High-Performance Photodetectors
摘要： Three-dimensional graphene (3D-Gr) with excellent light absorption properties has received enormous interest but in conventional processes to prepare 3D-Gr, amorphous carbon layers are inevitably introduced as buffer layers which may degrade the performance of graphene-based devices. Herein, 3D-Gr is prepared on germanium (Ge) using two-dimensional graphene (2D-Gr) as the buffer layer. 2D-Gr as the buffer layer facilitates in-situ synthesis of 3D-Gr on Ge by plasma-enhanced chemical vapor deposition (PECVD) by promoting 2D-Gr nucleation and reducing the barrier height. The growth mechanism is investigated and described. The enhanced light absorption as confirmed by theoretical calculation and 3D-Gr/2D-Gr/Ge with a Schottky junction improves the performance of optoelectronic devices without requiring pre- and post-transfer processes. The photodetector constructed with 3D-Gr/2D-Gr/Ge shows an excellent responsivity of 1.7 AW-1 and detectivity 3.42 × 1014 cmHz1/2W?1 at a wavelength of 1,550 nm. This novel hybrid structure which incorporates 3D- and 2D-Gr into Ge-based integrated circuits and photodetectors deliver excellent performance and has large commercial potential.
关键词： Buffer layer,Germanium,Photodetectors,Built-in potential,3D/2D-graphene
更新于2025-09-23 15:19:57
-
On the Question of the Need for a Built-In Potential in Perovskite Solar Cells
摘要： Perovskite semiconductors as the active materials in efficient solar cells exhibit free carrier diffusion lengths on the order of microns at low illumination fluxes and many hundreds of nanometers under 1 sun conditions. These lengthscales are significantly larger than typical junction thicknesses, and thus the carrier transport and charge collection should be expected to be diffusion controlled. A consensus along these lines is emerging in the field. However, the question as to whether the built-in potential plays any role is still of matter of some conjecture. This important question using phase-sensitive photocurrent measurements and theoretical device simulations based upon the drift-diffusion framework is addressed. In particular, the role of the built-in electric field and charge-selective transport layers in state-of-the-art p–i–n perovskite solar cells comparing experimental findings and simulation predictions is probed. It is found that while charge collection in the junction does not require a drift field per se, a built-in potential is still needed to avoid the formation of reverse electric fields inside the active layer, and to ensure efficient extraction through the charge transport layers.
关键词： perovskite solar cells,charge collection,built-in potential,charge transport layers
更新于2025-09-23 15:19:57
-
Evaluating the performance of InGaN/GaN multi-quantum-well solar cells operated at elevated temperatures via DC and small-signal AC analysis
摘要： InGaN/GaN multi-quantum-well (MQW) solar cells are investigated with temperature-dependent DC and AC analysis, and the effects of differing QW number and thickness are determined. The carrier transport is shown to be dominated by thermionic emission rather than tunneling at elevated temperature but limited by recombination outside the depletion region. Temperature-dependent AC parameters of the III-N MQW devices in high-level injection are determined through a refined AC circuit model of the device. It is shown that the use of AC small-signal analysis and its ability to extract stored charge in the QWs, the comparison of built-in potential to VOC, and other solar cell critical values allows a device designer insight not possible via DC analysis alone. This critical data suggests that the number of QWs and total depletion volume needs to be matched to the operational temperature of a given high temperature solar cell.
关键词： AC circuit model,multi-quantum-well,solar cells,recombination,VOC,DC and AC analysis,depletion region,built-in potential,InGaN/GaN,thermionic emission,carrier transport,temperature-dependent
更新于2025-09-19 17:13:59
-
Application of Al-Doped (Zn, Mg)O on pure-sulfide Cu(In, Ga)S2 solar cells for enhancement of open-circuit voltage
摘要： In this study, interfacial recombination observed by activation energy (Ea) is reduced with an improvement in the built-in potential (Vbi) by raising the conduction band minimum (EC) in Al-doped (Zn, Mg)O (AZMO) layer for pure-sul?de Cu(In, Ga)S2 (CIGS) solar cells. It is observed that the optical band gap in AZMO ?lms can be widened from 3.56 to 3.97 eV with increasing Mg/(Mg + Zn) ratio from 0 to 0.23, suggesting the shift of EC toward the vacuum level. AZMO layers with Mg/(Mg + Zn) ratio of 0–0.23 are applied as transparent conductive oxide (TCO) for the pure-sul?de CIGS solar cells. The open-circuit voltage is clearly enhanced from 0.641 to 0.713 V with increasing Mg/(Mg + Zn) ratio from 0 to 0.09 and then decreased to 0.651 V at Mg/(Mg + Zn) ratio of 0.23 in the AZMO layer. Reverse saturation current density (J0) was minimized to 9.4 × 10?7 A/cm2 at Mg/(Mg + Zn) of 0.09, although J0 was 4.7 × 10?6 A/cm2 in Al-doped ZnO (Mg/(Mg + Zn) of 0). From Mott-Schottky plot, it is observed that Vbi for the pure-sul?de CIGS solar cells gradually enhanced with an increase in Mg/(Mg + Zn) from 0 to 0.23 in the AZMO layer. These results suggest that Vbi improves by controlling EC in the TCO layer, which ultimately reduces the recombination at the hetero interface owing to strengthened electric ?eld.
关键词： Al-doped (Zn, Mg)O,Chalcopyrite,Thin-?lm solar cell,Built-in potential,Conduction band minimum,Cu(In, Ga)S2
更新于2025-09-16 10:30:52
-
Enhancing the Open-Circuit Voltage of Perovskite Solar Cells by Embedding Molecular Dipoles within their Hole-Blocking Layer
摘要： Engineering the energetics of perovskite photovoltaic devices through the deliberate introduction of dipoles to control the built-in potential of the devices offers the opportunity to enhance their performance without the need to modify the active layer itself. In this work, we demonstrate how the incorporation of molecular dipoles into the bathocuproine (BCP) hole-blocking layer of inverted perovskite solar cells improves the device open-circuit voltage (VOC) and consequently, its performance. We explore a series of four thiaazulenic derivatives that exhibit increasing dipole moments and demonstrate that these molecules can be introduced into the solution-processed BCP layer to effectively increase the built-in potential within the device, without altering any of the other device layers. As a result the VOC of the devices is enhanced by up to 130 mV with larger dipoles resulting in higher VOCs. To investigate the limitations of this approach, we employ numerical device simulations that demonstrate that the highest dipole derivatives used in this work eliminate all limitations on the VOC stemming from the built-in potential of the device.
关键词： Perovskite solar cells,Molecular dipoles,Device simulation,Built-in potential,Open-circuit voltage
更新于2025-09-11 14:15:04