Solution processable thin-film organic solar cells (TFOSCs) have attracted a lot of research attention in the past few decades, in the search for low-cost, flexible, and portable solar panels. In light of this, tremendous progress has been made in terms of improving materials design, device architecture, and ease of device fabrication processes. The choice of the donor and acceptor materials in the preparation of a polymer blend bulk heterojunction (BHJ) solar absorber medium is of great importance to the overall performance of organic solar cells (OSCs). The limitation in tuning the energy band structures of fullerene molecules poses significant challenges to the progress in BHJ organic solar cells. In an attempt to cater to the challenges, small-molecule non-fullerene acceptors (NFAs) came into the OSC research space with the possibility of altering the optoelectronic properties of the polymer molecules that bring OSCs closer to the realization of full-scale commercialization. This review discusses the role of NFAs in improving film morphology and reducing energy loss in TFOSCs. The recent development in engineering non-fullerene acceptors for solar energy conversion is presented and discussed in terms of reducing energy loss, improving solar cell performances.

Silver doped magnesium (Ag:Mg) bimetallic nanoparticles (BMNPs) were successfully synthesized using wet chemical processing. The collection of enhanced photocurrents is possible through metal nanoparticles in the photoactive layer of a thin‐film organic solar cell (TFOSC). This investigation employed poly‐3‐hexylthiophene(P3HT) and [6‐6]‐phenyl‐C61‐butyric acid methyl ester (PCBM) polymer blend solar absorbers in a conventional device structure. The solar cell performances were found to depend on the concentration of Ag:Mg BMNPs in the photoactive medium. Consequently, significant device performance was recorded for the solar cells containing Ag:Mg BMNPs at all doping levels compared to the un‐doped devices. Therefore, the highest power conversion efficiency (PCE) of 4.11% was achieved at a 1.5 wt% doping level with a high fill factor of 56% compared to the reference cell. The performance improvement in PCE constitutes a 79% improvement, which is much higher than undoped solar cells. This result was attributed to the occurrence of the localized surface plasmon resonance effect (LSPR), which is favorable for boosting the optical absorption and charge transport processes in TFOSC.

A Cd-doped ZnO nano-composite (Cd:ZnO) was synthesized using wet chemistry, and then incorporated into the photo-active layer of a thin film organic solar cell (TFOSC) to assist photon harvesting. The nano-composite (NC) formed different sized nano-structures that are beneficial to optical absorption and charge transport processes in the TFOSC. The effects on the NC were studied using a solar absorber medium composed of a poly(3-hexylthiophene) (P3HT) and 6-6-phenyl-C61-butyric acid methyl ester (PCBM) blend with standard device architecture: ITO/PEDOT:PSS/P3HT:PCBM/LiF/Al. The electrical and optical properties of the photoactive films were investigated at various doping levels of Cd:ZnO NC in the medium. The composite showed interesting local surface plasmon resonance, which significantly impacted on the performance of the cells. Consequently, the power conversion efficiency of the TFOSC grew by 84% compared to the reference cell. It is also noted that Cd:ZnO is environmentally stable and compatible for solution device processing.

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Tuning charge transport properties using silver‐cobalt bimetallic nanoparticles is investigated to enhance the photo‐current collection in polymer solar cells. The silver‐cobalt nanoparticles were not only augmenting the charge transport processes but also expected to trap light by way of reflection. The polymers blend consisting of poly‐(3‐hexylthiophene) (P3HT):[6,6]‐phenyl C61 butyric acid methyl ester (PC61BM) is used in the fabrication of polymer solar cells. The experimental results indicated that the solar cells' performance depended on the concentration of Ag/Co in the hole transport layer (HTL). Nevertheless, the high‐power conversion efficiency value of up to 4.21% was observed, at the concentration of 0.1% by weight, which is much higher than pristine solar cells due to improved measured photocurrents from the devices. This is a significant improvement in PCE by 66.4% compared to the undoped transport medium. Ag/Co nanocomposite is found to be more stable under ambient laboratory conditions.

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