Counter Electrodes for Quantum‐Dot‐Sensitized Solar Cells

Abstract

On the basis of the many advantages of quantum dots (QDs) including multiple exciton generation, high absorption coefficient, and band‐gap energy controllability, quantum‐dot‐sensitized solar cells (QDSSCs) have been studied for a few decades. However, despite the many advantages, improvement in the power‐conversion efficiencies of QDSSCs has been stagnated for a long time. To suggest a breakthrough in this stagnated QDSSC field, counter electrodes (CEs) have been focused on and are introduced in this Review article. Counter electrodes have been paid relatively less attention, whereas QDs and photoanode structures have been intensively studied. Nevertheless, it is an unchanged fact that CEs are also of considerable importance in QDSSCs, as they hold the possibility to enhance the performance of QDSSCs. In this Review, as an introduction, the basic working principles of QDSSCs are covered, and some widely used analytical tools for CEs are discussed, such as current density–voltage measurements, electrochemical impedance spectroscopy, cyclic voltammetry, and Tafel polarization measurements. Then, some interesting representative work on CEs is introduced. Given that various types of CEs exist, categorization of the CEs was conducted as follows: noble metals, metal sulfides, carbon derivatives, conducting polymers, and combinations of these types. With this Review article, it is hoped that insight will be gained to achieve a breakthrough in the stagnant field of QDSSC research.

Controlled growth of Cu3Se2 nanosheets array counter electrode for quantum dots sensitized solar cell through ion exchange

“…Typically, QDSSC is assembled by a transparent conductive substrate, a quantum dots loaded photoanode film, polysulfide electrolyte and a counter electrode (CE) [5]. As an important part of the photovoltaic device, CE plays a critical role in the electrons transport and oxidation of reduced ions [6], and thus is intensively investigated in recent years. In principle, high electro-catalytic and expected electrical conductivity activity are both required for an excellent CE [7].…”

Quantum dot sensitized solar cell: Recent advances and future perspectives in photoanode

“…Hwang et al [27] and Meng et al [28] have reviewed the role of conventional, noble metals, carbon electrodes and metal chalcogenide carbon electrode materials for enhancement of overall device performance. In addition, Hwang et al [27] have discussed the parameters like current voltage measurements, cyclic voltammetry, Tafel polarization measurement and electrochemical impedance spectroscopy measurements.…”

Cuprous sulfide on Ni foam as a counter electrode for flexible quantum dot sensitized solar cells

“…To optimize the experimental conditions for preparing and to evaluate the performance of the resultant Cu 2 S/Ni CEs, a model CdSeTe QDSC constructed by 8 conventional FTO based TiO 2 photoanode was studied. To compare the effects of substrate and catalysts on the performance of cells, Ni foam and Cu 2 S catalyst were individually replaced with FTO and NiS respectively, and Cu 2 S/FTO, NiS/Ni CEs were also prepared.…”

“…Therefore, a high electrical conductivity for the electrons collection, a large specific surface area for the electrolyte adsorption and a high catalytic activity for the reduction of S n 2-are supposed to be preferred characteristics for the desired CE in QDSCs. [8][9][10][11] Currently, the most widely used CEs in high efficiency QDSCs are brass foil and FTO (fluorine-doped SnO 2 ) glass supported copper sulfide (Cu x S) because of its superior catalytic activity. [12][13][14] The brass foil based CEs (Cu 2 S/brass) have the advantages of high catalytic activity, high conductivity and flexibility which may have potential applications in flexible QDSC.…”

“…However, Cu 2 S/brass CEs suffer from continuous corrosion of the brass substrate by polysulfide electrolyte, leading to mechanical instability of the electrode and leakage of electrolyte. 8,12 The FTO…”