Alternate redox electrolytes in dye-sensitized solar cells

Abstract

Dye-sensitized mesoscopic solar cell (DSC) has been intensively investigated as a promising photovoltaic cell. Redox electrolyte is important to determine the photovoltaic (PV) performance of the DSC devices, which has become the focus of this topic. In this contribution, recent advances in understanding and controlling of various redox couples are reviewed. Specially, we extend our discussion on the trends that enable iodide-free redox couples to be controllable and feasible for applications in the DSC with promising features. BackgroundMore and more people are realizing that the worldwide demand for energy has been massively increased and this situation will continue till a finial solution exists. However, several reports reveal that the production of oil, as one of the main energy sources, will soon be unable to keep up with the growing demand, thus leading to dire economic consequences. In order to sustain global political, economic and environmental stability, it is necessary to get an abundant supply of energy. Moreover, the development of carbon-free sources of energy becomes one of the major scientific challenges for us. As a potential alternative energy resource, solar energy has received extensive attention around the world after the energy crisis in 1970s [1]. Solar cells convert solar energy directly into electricity, which has become a major research interest within academia and industry. Approximately 90% of the PV units produced today are made from crystalline silicon (known as first generation solar cell), which is composed of large area p-n junctions, and others from thin films devices based on amorphous silicon (second generation solar cell, including CdTe, CIGS and other compound semiconductors). These devices based on p-n heterojunctions absorb part of the sunlight (absorption from 0.8-0.9 eV) and convert this light energy into electrical energy by the photovoltaic effect. Laboratory devices with efficiencies over 25% have been demonstrated, and the best commercial cells have now reached efficiencies of 17%-18% [2]. However, the high cost effectiveness of these devices still drives people to develop new type of solar cells expecting to possess high efficiency and low cost. The dominance of the photovoltaic market by inorganic solid-state junction devices is now being challenged by the emergence of a third generation of cells. Among them the dye-sensitized solar cell (DSC, also known as Grätzel cell) with a new type of charge separation mechanism is a promising potential candidate [3]. The DSC, with a sandwich structure, is mainly composed of a mesoporous nanocrystalline network of wide band gap semiconductor (typically TiO 2 ), a monolayer of dye molecules (such as ruthenium dye) attached to the semiconductor, a redox electrolyte (typically I − /I 3 − ) and a platinum counter electrode. Figure 1 shows the basic structure and operating principle of the DSC. Basically, upon illumination, electrons in the sensitizer dye are photo-excited to be the excited states, followed by an electron injecti...

Temperature Dependent Characteristics of Perovskite Solar Cells

“…If a PV device can be represented by an ideal diode, then Eq. 1 can be modified to include the photocurrent J L as follows …”

“…3. The influence of different elements, including R s , R sh , J 0 , J ph , and m of the diode, can be foreseen by simulation J ‐ V characteristics of solar cells . Figure a also presents a fitting curve (blue circuit) to the measured current‐ voltage characteristics of the device with using Eq.…”

Methods for promoting electrochemical properties of LiNil/3Col/3Mnl/3O2 for lithium-ion batteries

“…Meanwhile lithium-ion batteries have to compete with other types of energy storage materials [64][65][66]. The NCM would become a good competitor for power battery by promoting its special capacity, energy density, rate capability, cycle life, especially the thermal stability properties [67].…”

Electrochemical methods for the characterization and interfacial study of dye-sensitized solar cell

“…If only one semicircle appears on the frequency response region, M 1 * or M 2 * in Eqs. (11) and (12) can be set to zero.…”

“…Over this period, many new materials have been designed and synthesized to be used to improve the efficiency of DSSC. These include semiconductor oxides, organic sensitizers, redox couples and electrocatalysts for counter electrodes, all of which have been extensively reviewed elsewhere [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. In particular, various theoretical studies have also been conducted to elucidate the fundamental processes taking place in DSSC [18][19][20][21][22][23][24].…”