Zhenxiao Pan

Bio: Zhenxiao Pan is an academic researcher from South China Agricultural University. The author has contributed to research in topics: Quantum dot & Perovskite (structure). The author has an hindex of 15, co-authored 39 publications receiving 752 citations.

Quantum dot-sensitized solar cells

Abstract: Quantum dot-sensitized solar cells (QDSCs) have emerged as a promising candidate for next-generation solar cells due to the distinct optoelectronic features of quantum dot (QD) light-harvesting materials, such as high light, thermal, and moisture stability, facilely tunable absorption range, high absorption coefficient, multiple exciton generation possibility, and solution processability as well as their facile fabrication and low-cost availability. In recent years, we have witnessed a dramatic boost in the power conversion efficiency (PCE) of QDSCs from 5% to nearly 13%, which is comparable to other kinds of emerging solar cells. Both the exploration of new QD light-harvesting materials and interface engineering have contributed to this fantastically fast improvement. The outstanding development trend of QDSCs indicates their great potential as a promising candidate for next-generation photovoltaic cells. In this review article, we present a comprehensive overview of the development of QDSCs, including: (1) the fundamental principles, (2) a history of the brief evolution of QDSCs, (3) the key materials in QDSCs, (4) recombination control, and (5) stability issues. Finally, some directions that can further promote the development of QDSCs in the future are proposed to help readers grasp the challenges and opportunities for obtaining high-efficiency QDSCs.

One-step solution deposition of CsPbBr3 based on precursor engineering for efficient all-inorganic perovskite solar cells

Abstract: All-inorganic CsPbBr3 perovskite solar cells (PSCs) are attracting tremendous interest owing to their outstanding stability, especially under high temperature and humidity atmospheres. Limited by the low solubility of CsBr in most common solvents, it is still a great challenge to prepare high-quality CsPbBr3 films with sufficient thickness for PSC applications by the convenient one-step solution method. Herein, a novel precursor engineering strategy with the use of cesium acetate (CsAc) and ionic liquid methylammonium acetate (MAAc) is developed to increase the concentration of the CsPbBr3 precursor solution to 1.0 M and form uniform and high coverage CsPbBr3 films with large sized crystalline grains. The formation mechanism for this high-quality CsPbBr3 films is mainly due to tailoring the crystallization kinetics by MAAc. Correspondingly, high light-harvesting capacity and suppressed trap state related charge recombination are realized in the resultant PSCs. The champion CsPbBr3 PSCs achieve an efficiency of 7.37% (JSC = 7.40 mA cm−2, VOC = 1.22 V, and FF = 0.841). This device has also displayed good stability with negligible decay over a period of 1500 h under an ambient atmosphere with 30–35% relative humidity.

Improving the Efficiency of Quantum Dot Sensitized Solar Cells beyond 15% via Secondary Deposition.

Abstract: Low loading is one of the bottlenecks limiting the performance of quantum dot sensitized solar cells (QDSCs). Although previous QD secondary deposition relying on electrostatic interaction can impr...

Quantum dot sensitized solar cells with efficiency over 12% based on tetraethyl orthosilicate additive in polysulfide electrolyte

Abstract: The undesired charge recombination loss, occurring at photoanode/electrolyte interfaces, as well as the high redox potential of the currently used polysulfide redox couple electrolyte restrain the photovoltaic performance, particularly the open-circuit potential (Voc), of quantum dot sensitized solar cells (QDSCs). Herein, a valid and facile method to improve the performance of QDSCs is presented by modifying the polysulfide electrolyte with the addition of tetraethyl orthosilicate (TEOS). This approach is effective in a series of QDSC systems including the most commonly studied CdSe, CdSeTe, as well as Zn–Cu–In–Se (ZCISe) QDSCs. Experimental results indicate that with the use of 6 vol% TEOS additive in pristine polysulfide electrolyte at a staying time of 24 h, a remarkable enhancement in the conversion efficiency from 11.75% to 12.34% was obtained in ZCISe QDSCs. This photovoltaic performance is believed to be among the best result for all types of QD-based solar cells. The intrinsic mechanism for the performance improvement by the TEOS additive was verified by electrochemical impedance spectroscopy (EIS) and open-circuit voltage decay (OCVD) measurements.

Nanocrystalline semiconductors: Synthesis, properties, and perspectives

Abstract: The synthesis and study of so-called “nanoparticles”, particles with diameters in the range of 1−20 nm, has become a major interdisciplinary area of research over the past 10 years. Semiconductor nanoparticles promise to play a major role in several new technologies. The intense interest in this area derives from their unique chemical and electronic properties, which gives rise to their potential use in the fields of nonlinear optics, luminescence, electronics, catalysis, solar energy conversion, and optoelectronics, as well as other areas. The small dimensions of these particles result in different physical properties from those observed in the corresponding macrocrystalline, “bulk”, material. As particle sizes become smaller, the ratio of surface atoms to those in the interior increase, leading to the surface properties playing an important role in the properties of the material. Semiconductor nanoparticles also exhibit a change in their electronic properties relative to that of the bulk material; as th...

Quantum dot-sensitized solar cells

Abstract: Quantum dot-sensitized solar cells (QDSCs) have emerged as a promising candidate for next-generation solar cells due to the distinct optoelectronic features of quantum dot (QD) light-harvesting materials, such as high light, thermal, and moisture stability, facilely tunable absorption range, high absorption coefficient, multiple exciton generation possibility, and solution processability as well as their facile fabrication and low-cost availability. In recent years, we have witnessed a dramatic boost in the power conversion efficiency (PCE) of QDSCs from 5% to nearly 13%, which is comparable to other kinds of emerging solar cells. Both the exploration of new QD light-harvesting materials and interface engineering have contributed to this fantastically fast improvement. The outstanding development trend of QDSCs indicates their great potential as a promising candidate for next-generation photovoltaic cells. In this review article, we present a comprehensive overview of the development of QDSCs, including: (1) the fundamental principles, (2) a history of the brief evolution of QDSCs, (3) the key materials in QDSCs, (4) recombination control, and (5) stability issues. Finally, some directions that can further promote the development of QDSCs in the future are proposed to help readers grasp the challenges and opportunities for obtaining high-efficiency QDSCs.

Solar light harvesting with multinary metal chalcogenide nanocrystals

Abstract: The paper reviews the state of the art in the synthesis of multinary (ternary, quaternary and more complex) metal chalcogenide nanocrystals (NCs) and their applications as a light absorbing or an auxiliary component of light-harvesting systems. This includes solid-state and liquid-junction solar cells and photocatalytic/photoelectrochemical systems designed for the conversion of solar light into the electric current or the accumulation of solar energy in the form of products of various chemical reactions. The review discusses general aspects of the light absorption and photophysical properties of multinary metal chalcogenide NCs, the modern state of the synthetic strategies applied to produce the multinary metal chalcogenide NCs and related nanoheterostructures, and recent achievements in the metal chalcogenide NC-based solar cells and the photocatalytic/photoelectrochemical systems. The review is concluded by an outlook with a critical discussion of the most promising ways and challenging aspects of further progress in the metal chalcogenide NC-based solar photovoltaics and photochemistry.

Interfacial Strain Release from the WS2/CsPbBr3 van der Waals Heterostructure for 1.7 V Voltage All-Inorganic Perovskite Solar Cells

Abstract: Perovskite lattice distortion induced by residual tensile strain from the thermal expansion mismatch between the electron-transporting layer (ETL) and perovskite film causes a sluggish charge extraction and transfer dynamics in all-inorganic CsPbBr3 perovskite solar cells (PSCs) because of their higher crystallization temperatures and thermal expansion coefficients. Herein, the interfacial strain is released by fabricating a WS2 /CsPbBr3 van der Waals heterostructure owing to their matched crystal lattice structure and the atomically smooth dangling bond-free surface to act as a lubricant between ETL and CsPbBr3 perovskite. Arising from the strain-released interface and condensed perovskite lattice, the best device achieves an efficiency of 10.65 % with an ultrahigh open-circuit voltage of 1.70 V and significantly improved stability under persistent light irradiation and humidity (80 %) attack over 120 days.