Due to the negative impact and possible run out of fossil fuels, the use of an alternative source of energy, which is plentiful, is crucial. The use of sunlight to produce energy by means of photovoltaic cell devices is the perfect approach to deal with the disadvantages of fossil fuels. Now, the photovoltaics that are already in market because of their power conversion efficiency (PCE) and stability are based on inorganic materials. These inorganic materials are however faced with drawbacks such as toxicity and high fabrication cost. Changing inorganic materials to organic overcome those drawbacks making organic photovoltaic cells (OPVs) of importance. The problem with the OPVs is the low PCE and low stability. For decades now, researchers have been trying to improve the performance of OPVs by modifying active layer materials with the PCE of over 19% reached. This performance was achieved by performing intensive investigations to understand how the materials used in OPVs affect their performance. Our work highlights recent advancements on how the structures and chemical makeups of the active layer materials affects photovoltaic processes and performance in terms of power conversion efficiency and stability. It further sheds lights on the performance optimization of OPV and the relationship between these optimization conditions and OPV performance. The use of different substituents on the same donor or acceptor material has different optimal conditions. Furthermore, we showed how addition of different third components in the active layer have different optimal concentration point. This review also highlights and suggests a possible way to improve stability of OPVs through modification of the active layer. To date, some studies showed that incorporation of third component in the active layer led to over 97% stability after more than 1000 h.This article is protected by copyright. All rights reserved.
