The solar photovoltaic (PV) cell is a prominent energy harvesting device that reduces the strain in the conventional energy generation approach and endorses the prospectiveness of renewable energy. Thus, the exploration in this ever-green field is worth the effort. From the power conversion efficiency standpoint of view, PVs are consistently improving, and when analyzing the potential areas that can be advanced, more and more exciting challenges are encountered. One such crucial challenge is to increase the photon availability for PV conversion. This challenge is solved using two ways. First, by suppressing the reflection at the interface of the solar cell, and the other way is to enhance the optical pathlength inside the cell for adequate absorption of the photons. Our review addresses this challenge by emphasizing the various strategies that aid in trapping the light in the solar cells. These strategies include the usage of antireflection coatings (ARCs) and light-trapping structures. The primary focus of this study is to review the ARCs from a PV application perspective based on various materials, and it highlights the development of ARCs from more than the past three decades covering the structure, fabrication techniques, optical performance, features, and research potential of ARCs reported. More importantly, various ARCs researched with different classes of PV cells, and their impact on its efficiency is given a special attention. To enhance the optical pathlength, and thus the absorption in solar PV devices, an insight about the advanced light-trapping techniques that deals with the concept of plasmonics, spectral modification, and other prevailing innovative light-trapping structures approaching the Yablonovitch limit is discussed. An extensive collection of information is presented as tables under each core review section. Further, we take a step forward to brief the effects of ageing on ARCs and their influence on the device performance. Finally, we summarize the review of ARCs on the basis of structures, materials, optical performance, multifunctionality, stability, and cost-effectiveness along with a master table comparing the selected high-performance ARCs with perfect AR coatings. Also, from the discussed significant challenges faced by ARCs and future outlook; this work directs the researchers to identify the area of expertise where further research analysis is needed in near future.

For the past one hundred years, lots of easily accessible petroleum fuel has been burned out by humankind in inefficient engines. In this regard, present-day engine researchers face a formidable challenge to achieve the goal of significant improvements in both thermal efficiency and fuel economy. Although the direction to reach this target is critical, homogenous charge compression ignition (HCCI) is just another combustion concept to achieve this target. By the way, this work investigates the combustion phenomena of the HCCI engine by external mixture formation technique. In a nut-shell, an endeavor has been made in this work to prepare homogeneous mixture outside the combustion chamber using a fuel vaporizer system to form a uniform fuel–air mixture. The fundamental research experiments were carried out with vaporized diesel and vaporized e-diesel blends (10% and 20% ethanol substitution by volume), and the results were compared with conventional diesel engine operation. In HCCI mode, the maximum rate of pressure rises and the maximum rate of heat-release significantly reduced with increase of ethanol concentration in diesel. The experimental outcomes exposed that when HCCI engine is operated with e-diesel blend, smooth engine operation is apparent