Different ratio incorporation of Ag/TiO₂ core–shell nanowires (ATCSN) into TiO₂ as an electron transport layer of perovskite solar cells (PSCs) is studied. This structure can prevent the formation of silver halides between perovskite and silver nanowire. It is found that because of the effective improvement of light absorption and separation of photo-generated electron–hole pairs, the introduction of ATCSN leads to increase of short current density and photoelectric conversion efficiency (PCE) of PSCs. 20 mg incorporation of ATCSN PSCs exhibits the best performance of PCE and a 17.7% increase is achieved compared to the control sample.

Solar energy is a cornerstone of the future global sustainable energy system. The book chapter outlines how performance and energy yield increase will have to evolve concurrently to make PV a major electricity source and how PERC-technology is an important milestone in achieving this.

The author provides a historical review of research into the atmospheric pressure chemical vapour deposition (APCVD) of Al₂O₃ for silicon surface passivation in solar cell devices, considering deposition temperature influence on excess carrier lifetime, film thickness and interface state density.

The authors review developments in the use of PECVD in the growth of AlO_x layers for solar cells. They consider the microwave PECVD and inductively coupled plasma PECVD methods, and the characteristics of layers grown by the 2 techniques, Si surface passivation, and solar cell applications.

In this book chapter, the authors summarize the main developments and improvements within the last 25 years which enabled the industrialization of the lab-type PERC solar cell concept. In particular, we describe the historic development and current status of key industrial PERC manufacturing process steps such as the rear passivation layer, typically applying an AlOx/SiNy layer stack, as well as the local Al rear contact formation by laser ablation, Al screen printing and subsequent firing. At the end of this chapter, an outlook is provided on future development opportunities such as further efficiency increases and bifacial PERC applications.

The book chapter shows that surface passivation technologies have played a crucial role in the development of industrial silicon solar cells over the past 40 years, and they will continue to do so in the future. The authors describe a variety of surface passivation techniques that will help to take industrial silicon solar cells to even greater heights, ensuring ongoing reductions of the levelized cost of electricity (LCOE) from PV systems and their global deployment on a massive scale.

The book chapter reviews the process of spatial Al₂O₃ atomic layer deposition (ALD). Aspects covered include: time-based versus spatial methods; proof of principle spatial ALD; spatial ALD applications; from the proof of principle to InPassion® LAB; transform from Lab to Fab-InPassion® ALD; second generation-InPassion® ALD; combining the stack layers.

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.

Organic bulk heterojunction solar cell based on poly 3hexylthiophene (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) blend as photoactive layer had been electrically simulated and analyzed at different thickness using general-purpose photovoltaic device model (GPVDM) software. Conjugate polymer P3HT acted as an electron donor, whereby PCBM acts as an electron acceptor in the device. The electrical simulation is performed at three different thicknesses of 50 nm, 100 nm, and 200 nm with P3HT/PCBM blend and hetero-layer configurations, respectively. The simulation analysis clearly demonstrated that both device configurations exhibited current-voltage (I-V) characteristics with highest short-circuit current density (J_sc) value of 2.26 mA/cm² with P3HT/PCBM of blend configuration at 200 nm thickness. However, an open-circuit voltage (V_oc) and fill factor (FF) showed a constant value, which 0.55 V and 0.72 a.u., respectively, for both device configurations. The obtained value of solar cell parameters was then analysed and compared with experimental data. This simulation work strongly reveals that different thickness of photoactive material affects the electrical performance even in different organic solar cell configurations.

Solar cells made of single-crystalline silicon, as alternative energy sources, became the most widely used solar cells in recent years. The mainstream manufacturing approach is to process the cells from Si wafers, and then assemble these cells into photovoltaic (PV) modules. However, the direct conversion of solar energy into electricity using the photovoltaic effect suffers from low efficiency. Thus, increasing the conversion efficiency at low production costs becomes the main goal of solar cells manufacturers. One way to increase the efficiency of a solar cell is to use an ultra-wide layer of intrinsic semiconductor as the depletion region of a P-N junction. Computer simulation shows that an intrinsic layer of 1 μm thickness results in an increase of the photovoltaic conversion efficiency by 4.85% for conventional single-crystalline silicon P-N junction. In our work, we present a novel geometrical concept of a PIN structure for PV applications. The width of the intrinsic layer in our construction is 5-20 mm. Moreover, in our novel structure, the light irradiation acts directly on the active region of the PV cell, which enables bi-facial irradiation and results in ~28% conversion efficiency. A low-cost fabrication is ensured in our design due to a new manufacturing technology by eliminating some expensive processes, such as photolithography. The feasibility proof of the novel concept in mono-crystalline silicon solar cells is presented. We demonstrate simulation results and preliminary experimental results confirming our approach. Detailed computer simulations show that the voltage drop and accordingly the high and constant electric field within the intrinsic region of the structure take place for sufficiently small sizes of the region (up to 200 - 300 nm). With extension of the intrinsic region length the field becomes extremely uneven with peak values at the p-i and i-n junctions. The field strength falls from tens of thousands Volts per centimeter to hundreds of Volts per centimeter for 5 μm intrinsic zone and after 10 μm the field practically disappears. Analysis of the simulation results, electrons and holes concentration profiles, space charge and electric field distributions, brings the idea that the uncompensated charges of the donors and acceptors at the n-i and p-i junctions are the source of the built-in field in the intrinsic region. The simulation of the p-i-n structure equilibrium state was done by the Silvaco's ATLAS silicon device simulator.

Cadmium selenide (CdSe) thin films were prepared on indium tin oxide substrate by an alternating cold–hot method, in which cadmium nitrate solution was used as a cold deposition solution, while sodium selenite and potassium borohydride mixed solution was used as a hot deposition solution. The influences of the preparation conditions such as the concentration of Cd(NO₃)₂, the number of deposition cycle and the cycle time, on the photoelectric performance of the sample under simulated sunlight were explored. The results show that the CdSe thin film prepared under the reaction conditions of 0.06 mol/l Cd(NO₃)₂ at the tenth deposition cycle (30 s per cycle) reaches the highest photovoltage of 0.285 V. Under the simulated solar illumination, the open-circuit voltage and short-circuit currents are 0.419 V and 5.57 mA/cm², respectively. X-ray diffraction indicates that the strongest diffraction peak at 42.215° of the (111) crystal plane is corresponding to 15.15 nm CdSe nanocrystals. Scanning electron microscopy observation shows that the thickness of the CdSe film is about 200 nm and the size of the spherical and uniformly dispersed nanocrystals is around 50 nm.

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.

The rear point-contact fabricated through the laser-opening technique for mass production was applied on the photovoltaic cells. Laser opening, different layers for passivation (SiO₂) and protection (SiN _X ) were employed to investigate their impact on the performances of solar cells. The SiN _X layer protects the SiO₂ layer from being burnt through by aluminium paste at the co-firing step. A conversion efficiency (η) of 16.91% with an open-circuit voltage of 628 mV was obtained for the optimal cell, a stack structure with SiO₂ and SiN _X layers, which also achieves a lower contact resistance of 6.66 mΩ·cm² and a higher light-beam-induced current of 80.77 mA/cm². The optimal cell also showed longer lifetime and 3–4% increased quantum efficiency in the visible wavelength range. Therefore, the developed process has simplicity and reliability, is fast and cost-effective and could be applied to industrial applications.

Two advanced fabrication methods are introduced: the hydrogen peroxide (H₂O₂)-added chemical bath deposition technique and molybdenum (Mo) back-contact formation under 3 kW sputter power. The parameters of the short circuit current density (J _SC) and conversion efficiency (η) were improved over standard cells when the ZnS buffer layer was deposited in the H₂O₂-added chemical solution. Otherwise, the fill-factor and η were best at 3 kW Mo sputtering power conditions. Advanced fabrication methods are realised to improve cell performance without modifying the chemical composition of the Cu(In,Ga)Se₂ absorption layer.

The novel structure of a solar cell is presented that has the metal–oxide-semiconductor diode at the side wall of the power generation layer. The influence of the field-effect on the recombination of carriers is simulated and the increase of the conversion efficiency of the solar cell by the gate voltage application is discussed. In addition, the relationship between the effect of the gate voltage application on the conversion efficiency, the lifetime and the surface recombination velocity is discussed.

A start-up circuit, used in a micro-power indoor light energy harvesting system, is described. This start-up circuit achieves two goals: first, to produce a reset signal, power-on-reset (POR), for the energy harvesting system, and secondly, to temporarily shunt the output of the photovoltaic (PV) cells, to the output node of the system, which is connected to a capacitor. This capacitor is charged to a suitable value, so that a voltage step-up converter starts operating, thus increasing the output voltage to a larger value than the one provided by the PV cells. A prototype of the circuit was manufactured in a 130 nm CMOS technology, occupying an area of only 0.019 mm2. Experimental results demonstrate the correct operation of the circuit, being able to correctly start-up the system, even when having an input as low as 390 mV using, in this case, an estimated energy of only 5.3 pJ to produce the start-up.

TiO₂ spindles with high crystallinity were synthesised by a two-step solvothermal reaction with the aid of diethylamine. Compared with Degussa P25, the dye sensitised solar cell (DSSC) based on a TiO₂ spindles photoanode demonstrated superior characteristics including higher affinity to N719 dye, higher light scattering effect than P25, better conductance and longer recombination lifetime. Photovoltaic measurement indicated that the TiO₂ spindles-based DSSC possesses higher short-circuit current density (J_sc) and open-circuit voltage (V_oc), hence, a 29% higher overall photovoltaic performance (η) than that of P25 was achieved.

The authors simulate both conventional and doping superlattice GaInNAs solar cells. They show that for a conventional cell with 1 µm diffusion lengths the maximum possible efficiency is approximately 9.5% and for 0.1 µm diffusion lengths it is 6.5% as the device must be relatively thin. Doping superlattice structures with varying number of layers and different layer thicknesses are simulated to find the design which yields the highest efficiency. A high number of thin layers allow a high percentage of incident photons to be absorbed, and carrier separated increasing the short-circuit currents leading to efficiencies close to 12%.

This presentation discusses some key characteristics of polymers and several polymer-based electronic devices such as polymer light-emitting diodes, photovoltaic diodes, organic solar cells, field-effect transistor, and electrophoretic display. (31 pages)

One of the major drawbacks of photovoltaic systems is the high generation cost. To address this problem, the US Defense Advanced Research Projects Agency initiated a study to create a thousand 10 cm² solar cells with over 50% efficiency, providing 500 mW in full sunlight, with reasonable manufacturing costs. Called the Very High Efficiency Solar Cell (VHESC) program, it hopes to take advantage of recent advances in nanotechnology by using engineered biological molecules to guide the assembly of inorganic materials into regular 3D structures, with dimensional and assembly control unattainable using current technologies. The program also hopes to benefit from the recent introduction of tools and processes to design and cost-effectively fabricate small-feature, complex, broad-spectrum non-imaging optics.

(Ga,In)(N,As) could be a promising material for use in monolithic four-junction solar cells since it can be grown lattice-matched to substrates such as GaAs and Ge, and its bandgap of 1 eV is complementary to that of the three other semiconductors Ge, GaAs and (Ga,In)P. The growth by molecular beam epitaxy of (Ga,In)(N,As)-based solar cells is reported. It was checked by high-resolution X-ray diffraction that the 1-μm-thick (Ga,In)(N,As) layers were lattice-matched to GaAs. The spectral responses of the solar cells provide evidence that (Ga,In)(N,As) converts photons with energy down to 0.9 eV. The comparison with reference GaAs solar cells indicates, however, a degradation of the short-circuit current, revealing short minority-carrier diffusion lengths. A (Ga,In)(N,As) 2 mm×2.5 mm solar cell with a p–i (Ga,In)(N,As) n-GaAs structure delivers a 2.1 mA/cm² short-circuit current and has an open-circuit voltage of 0.264 V under natural solar illumination (air mass ∼1.5).

Thin film polycrystalline silicon solar cells on foreign substrates are viewed as one of the most promising approaches to cost reduction in photovoltaics. To enhance the quality of the film, the use of ‘seeding layers’ prior to deposition of active material is being investigated. It has been shown that a phenomenon suitable to create such a seeding layer is the aluminium-induced crystallisation of amorphous silicon. Previous work mainly considered glass as the substrate of choice, thereby introducing limitations on the deposition temperature. Results concerning the application of such a technique to ceramic substrates (allowing the use of high-temperature CVD) are described. Also, the first reported results of a solar cell made in silicon deposited on these seeding layers are presented.

Pulsed plasma enhanced chemical vapour deposition (PECVD) involves modulation of standard 13.56 MHz RF plasma in the kilohertz range. This allows an increase in the electron density during the ‘ON’ cycle, while in the ‘OFF’ cycle, neutralising the ions responsible for dust formation in the plasma. The authors report the development of state-of-the-art nanocrystalline Si (nc-Si:H) materials using a pulsed PECVD technique with 220 crystallite orientation, grain size of ∼200 Å, low O concentration and a minority carrier diffusion length L_d of ∼1.2 μm. The crucial effects of the p/i interface and the incubation layer have been investigated and an efficiency of ∼7.5% for a single junction nc-Si:H p-i-n device has been achieved for an i-layer thickness of 1.4 μm, using non-optimised textured substrates.

A review of recombination in silicon thin-film solar cells studied by means of electrically detected magnetic resonance (EDMR) is presented. It is shown that the EDMR results in μc-Si:H p-i-n solar cells can be described by a simple diffusion model that was developed for crystalline silicon p-n junctions assuming that recombination is dominated by dangling bonds in the space charge region. The results are compared to a-Si:H p-i-n cells and discussed in a recombination model involving the excited states of charged dangling bonds.