Here to determine the thermal stability of buffered layer organic solar cell (BL-OSC), the effect of post anneal treatment has been studied. To investigate the effect of post annealing, the organic solar cells (OSCs) are annealed at the 120°C for different time duration. It has been observed that the BL-OSC structure exhibits the better thermal stability. Further, as the authors vary the post-annealing time duration from 0 min to 20 min, the power conversion efficiency (PCE) in the case BL-OSC drops by ∼20%, whereas in conventional OSC, the PCE drops by ∼35%. This annealing dependent study shows that, in conventional OSC structure an increase in phase segregation between donor and acceptor molecules reduces exciton dissociation and charge separation, this leads to sharp increase in series resistance and significant reduction in fill factor of the device. Whereas in the case of BL-OSS, there is a minimum reduction in the fill factor, which also determines the superior carrier collection and low recombination on the elevated annealing conditions. Further, the experimental results show that, in comparison with the conventional OSC structure, inserting the pure P3HT interlayer between PEDOT:PSS (hole transport layer) and P3HT:PCBM (photoactive layer) improves the PCE of the device by 34%.

To improve light absorption, in this study, the narrow band gap highly-ordered free-standing hydrogenated amorphous germanium nanoparticles (a-Ge:H NPs) were introduced into the CH₃NH₃PbI_3−x Cl _x films. Here, the NPs were fabricated by means of the radio frequency plasma enhanced chemical vapour deposition system. The effects of hydrogen dilution ratio (RH) on the microstructure and bonding configuration of a-Ge:H NPs were investigated by Raman, transmission electron microscopy and Fourier transform infrared spectroscopy measurements. As RH increases, an improvement in the structure order of a-Ge:H NPs was observed. Compared with the pure CH₃NH₃PbI_3−x Cl _x films, the light absorption of the hybrid a-Ge:H NPs/CH₃NH₃PbI_3−x Cl _x active layers was improved, and the surface coverage of the hybrid active layers nearly reached 100%. This new finding provided a novel way to solve the universal unfavourable surface coverage problem that existed in the ultrasonic spray-coating process. Meanwhile, compared with the device that is based on pure CH₃NH₃PbI_3−x Cl _x films, due to the enhanced light absorption in the visible range, a ∼14.6% enhancement in the power conversion efficiency was achieved based on the hybrid a-Ge:H NPs/CH₃NH₃PbI_3−x Cl _x active layers.

The objective of this study is to present an economic analysis (EA) of actual installed photovoltaic (PV) projects considering Gulf Cooperation Council countries climate conditions. The two analysed PV systems are commissioned in Kuwait and they were chosen to be the scope of this study since the availability of their characteristics. The first system is installed on a school and equipped with thin film (copper indium gallium selenide) solar modules of efficiency equal to 14% and the other system is installed on a commercial building and equipped with monocrystalline solar modules of efficiency equal to 17%. The EA consists of studying the financial parameters related to the two previous projects using two different calculation tools. One tool is developed and presented in this study that is the EA calculator and the other tool is the existing solar advisory model software. The two calculation tools’ results almost match with slight differences considered negligible, so the developed EA calculator is considered validated. As a conclusion, the impact of renewable energy (RE) costs on future investments in RE technologies and especially on PV projects is being evaluated.

The study proposes designs using 2D photonic crystal (PhC) structure-based thin film heterojunction gallium arsenide (GaAs) solar cell with a periodic pattern having PhC structure extends from top transparent conducting oxide (TCO) to inside the p-AlGaAs window layer placed just above the active layer of GaAs material in one design and in another PhC structure is etched only in TCO. The work presents the comparative analysis of the proposed structure with Lambertian light trapping limits and the planar cell, taken as reference. The study is also performed for double-layer anti-reflective coating (ARC) structure. The study presents the quantitative analysis of the effect of PhC structure in the performance of the design and how the effect varies with the thickness of absorption layer. It has been found that a considerable increase in efficiency has been achieved, especially for thinner active layers, demonstrating the advantage of a wavelength-scale, PhC-based structures for thin-film solar cells. The results have shown that PhC structure (etched till inside p-AlGaAs)-based solar cell exceeds the efficiency of the double ARC-based structure by more than 18% for 50 nm thin active layer cell. The parameters have been optimised and calculated by means of rigorous coupled wave analysis (RCWA).

The surface passivation for InGaN/GaN multilayer solar cells was investigated, and it was confirmed that the device with an atomic-layer-deposited (ALD) Al₂O₃ passivation film showed high internal and external quantum efficiencies of 99 and 84%, respectively, along with a high energy conversion efficiency of 1.31% under a 1-sun air-mass 1.5 global illumination. The current−voltage characteristics indicated that the ALD Al₂O₃ film improved the surface electrical stability. The carrier lifetime measurements revealed that the ALD Al₂O₃ film reduced the surface carrier recombination rate and thereby contributed to the improvement of the solar cell performance in a short wavelength region.

A low-cost, highly reflective, liquid organic nanostructure silver conductor with superior conductivity, using back contact reflectors in amorphous silicon (a-Si) single-junction superstrate configuration thin-film solar cells produced using a non-vacuum screen printing process is proposed. The conductive paste is composed of Ag nanowires (Ag NWs) mixed with an Ag nanostructure (Ag NS) sheet. The paste is referred to as ‘Ag NWS’. A comparison of silver conductor samples with vacuum-system-sputtered silver samples indicated that the short-circuit current density (J _sc) and the open-circuit voltage (V _oc) of Ag NWS conductor cells exceeded 0.22 mA/cm² and 66 mV, respectively. The Ag NWS conductor with back contact reflectors in solar cells was analysed using external quantum efficiency measurements to effectively enhance light-trapping ability in a long wavelength region (580–700 nm). The cells constructed using the optimised Ag NWS demonstrated an increase of approximately 6.1% in power conversion efficiency under AM 1.5 illumination. These results indicated that the Ag NWS conductor back contact reflector layer is a suitable candidate for high-performance a-Si thin-film solar cells.

A multi-layered film with a TiO₂-based nanotubes/nanoparticles/nanotubes sandwich structure has been developed to increase light-harvesting efficiency by enhancing light scattering. Compared to a double-layered film of nanotubes/nanoparticles, the sandwiched film exhibited greatly improved light-absorption properties. An obviously improved total energy-conversion efficiency of 6.11% was obtained in the sandwiched film, which is 27.3, 46.1 and 213% higher than those of the double-layered film, nanoparticle film and nanotube film, respectively. A possible mechanism for the enhancement of light harvesting in the sandwiched film is proposed, whereby the observed enhancement is owing to effective scattering by the bottom layer and reflection of escaped light by the top layer.

Optimum heat treatment processes for carbon nanotubes (CNTs) paste counter electrodes with better electrochemical performance are investigated. Half-cells were fabricated to examine the electrochemical properties of the CNT paste counter electrode. Proposed is a two-step heat treatment process and an optimum sintering temperature for CNT paste counter electrodes.