The need for large scale low carbon solar electricity production has become increasingly urgent for reasons of energy security and climate change mitigation. Third-generation solar cells (SCs) are solution processed SCs based on semiconducting organic macromolecules, inorganic nanoparticles or hybrids. This review considers and compares three types of promising 3rd-generation SCs: polymer:fullerene, hybrid polymer and perovskite SCs. The review considers work reported since an earlier review (Saunders et al., Adv. Colloid Interface Sci., 2008, 138, 1) and highlights the great progress that has been made in each area. We consider the operation principles for each SC type and also review the state-of-the-art devices. The polymer:fullerene and hybrid polymer SC open circuit voltages are compared to values predicted from the well-known Scharber equation and similarities and differences discussed. The perovskite SCs are also considered and their remarkable rate of power conversion efficiency performance increase is discussed. The review considers the requirements for large-scale deployment in the contexts of semiconducting polymer and hole transport matrix synthesis and materials selection. It is concluded that the 3rd-generation SC technologies discussed here are well placed for major contribution to large scale energy production. (This has already been partially demonstrated for polymer:fullerene SCs.) Looking further ahead we propose that several of the 3rd-generation SCs considered here have excellent potential to provide the low cost large-scale deployment needed to meet the terawatt challenge for solar electricity generation.

We review structurally complex hydrogels and consider key parameters controlling their structures and properties and conclude by suggesting a framework for assessing the novelty of new gels.