A review on quantum dot sensitized solar cells: Past, present and future towards carrier multiplication with a possibility for higher efficiency

Quantum Dot Sensitized Solar Cells are considered as the potential third generation solar cells due to their suitable optoelectronic properties for photovoltaic response. The possibility of size and composition tunability makes quantum dots as relevant absorber materials to match the wider solar spectrum more efficiently. In conjunction, the possibility of multiple electron-hole pair generations at the cost of single photon i.e. multiple carrier generation is showing potential to overcome the theoretical single junction power conversion efficiency limitations. Quantum dot sensitized solar cells are showing power conversion efficiencies up to 12%, very close to its counterpart dye sensitized solar cells. However, QDSSCs efficiencies are still lagging behind the conventional solid state single junction solar cells. In this review, we will discuss the initial evolution of quantum dot sensitized solar cells with their microscopic working principles. The review will also address development of key building blocks and factors such as various interfaces in QDSSCs, carrier transport and recombination across different interfaces, affecting the power conversion efficiency. Further, fundamental concepts of carrier multiplication and possible theoretical models for multiple exciton generation are discussed towards their impact on the power conversion efficiencies of quantum dot sensitized solar cells.