In this contribution, Automat FOR Simulation of HETero-structures v2.5 software was used for unveiling the photovoltaic performance and thermal stability of relatively less explored TiO2/c-Si heterojunction solar cell architecture based on 110 μm wafers. Firstly, the dependence of the photovoltaic performance on the emitter layer, i.e. the TiO2 layer, was explored by varying its different characteristics: thickness, carrier concentration and the defect density at the TiO2/Si interface. The study revealed that the power conversion efficiency might be as high as 16.34

The choice of the best possible TOPCon solar cell architecture in terms of photovoltaic performance, thermal stability, and bifaciality has been one of the most fundamental issues to be addressed. Accordingly, a theoretical approach with the help of Automat FOR Simulation of HETero‐structure simulation software has been adopted to conduct a detailed comparative analysis among n‐TOPCon, p‐TOPCon, and TOPCoRE solar cells based on tentative future wafer thickness, i.e., 110 μm. Initially, the sole impact of the thickness of the ultrathin SiO x layer is unveiled and it is realized that the maximum power conversion efficiency may reach to 24.35%, 23.72%, and 24.45% for n‐TOPCon, p‐TOPCon, and TOPCoRE solar cells; respectively; however, the optimized thickness of SiO x layer is quite low. Subsequently, pinholes within 1.5 nm SiO x tunneling layer are incorporated and it is observed that adequate power output may be realized upon the optimization of the pinhole density. To realize further the cost‐cutting option, the impact of wafer lifetime on the device performance is deduced. Eventually, the operating temperature is varied from 275–375 K with an interval of 25 K to examine the thermal stability of the devices which have demonstrated almost similar thermal degradation within the tested region.

In this work, doped and dopant-free carrier-selective passivating contacts have been incorporated in Interdigitated Back Contact solar cells. TCAD simulation study was done to check the performance of an IBC-SHJ (Silicon Hetero-Junction) and IBC-POLO (POLy-silicon on Oxide as seen in TOPCon) cell structures for both p and n-type wafers. The IBC-POLO structure was also repeated with HfO2 and ZrO2 over electron transport and hole transport layers, respectively. Simulation study was done by replacing the doped silicon layers with dopant-free Transition Metal Oxides (TMOs). NiO was used as a dopant-free hole-selective contact, whereas Nb2O5 was used a dopant-free electron-selective contact. The fabrication of these materials is non-hazardous and at low temperatures due to which they are preferable over the doped Si layers that require toxic gases like phosphine, diborane, etc. and may also require high temperatures. For example, poly-Si layer applied in IBC-POLO requires an annealing temperature of over 800 °C; similarly, the diffusion of Front Surface Field (FSF) layer in normal IBC cells also requires the same high temperature. Temperature variation was done on these structures to check the dependence of solar PV parameters of each IBC structure on different temperatures. Same variation was checked with minority carrier lifetime of the silicon wafer.

Transparent conducting oxides (TCOs) are enormously endorsed as electrodes in solar photovoltaics industry due to featuring excellent opto-electronics properties. Indium tin oxide (ITO) has been quite popular in TCO industry as it features superior electrical conductivity along with higher optical transparency in comparison with other popular TCO materials. Nevertheless, the usage of ITO has been found to be limited as front electrodes in thin film silicon solar cells due to its sustainability issue in H 2 plasma and less abundance of indium. In contrast, other promising TCO materials such as aluminium doped zinc oxide (AZO), boron doped zinc oxide (BZO), gallium doped zinc oxide (GZO) etc. are found to quite durable in H 2 plasma environment and relatively cost-effective too. However, the opto-electronic qualities of such films are generally inferior to the ITO films. As a result, in this contribution, a thorough study has been carried out on relatively less explored ITO/AZO bilayer TCO films. A detailed comparison in terms of the structural, morphological and opto-electronic properties among single layer ITO films, single layer AZO films and ITO/AZO bilayer films has been made. The study has been further extended to realize the impact of using ITO/AZO bilayer films instead of single layer AZO film as front electrodes in single junction a-Si:H solar cells. The best single junction a-Si:H solar cell which featured ITO/AZO bilayer as front electrode and was fabricated into superstrate configuration demonstrated significant gain in short-circuit current density ( J sc ) of 0.79 mA/cm 2 and hence, power conversion efficiency of 0.37% (absolute) compared to the cells which comprised of single layer 900 nm thick AZO film as front electrode (reference cell). The improvement in J sc might be attributed to the realization of superior figure of merit (FOM) of bilayer samples to its counterpart.

In the present work, Automat FOR Simulation of HETerostructures (AFORS-HET v2.5) simulation software was used to investigate the performance of p-type tunnel oxide passivated contact (p-TOPCon) solar cells. Firstly, the influence of SiO x thickness on the device performance at different rear surface recombination velocity (SRV) was studied thoroughly; the same was followed by the incorporation of pinholes at different oxide thickness to realize the impact of pinhole density (D ph ) on the charge carrier transport mechanisms through the ultra-thin SiO x tunneling layer. Next, the doping concentration of p + poly-Si layer was varied to reveal its impact on the device output and it was noticed that presence of pinholes might facilitate the transformation of charge carriers through ultra-thin SiO x tunneling layer even at relatively lower poly-Si doping concentration. Furthermore, the consequence of wafer thickness at different wafer lifetime and at different front SRV on the performance of p-TOPCon solar cells was studied thoroughly. A relative analysis on the device performance in between the conventional TOPCon and TOPCore (TOPCon with p-type wafer and n + poly-Si as rear emitter) solar cell architecture based onto p-type base substrate was conducted. Eventually, an in-depth comparative analysis of the thermal stability among TOPCon, TOPCore and baseline BSF (back surface field) solar cells was carried out for both thicker and thinner wafers. The role of pinholes on the thermal stability of the devices was also pinpointed and it was yielded that our optimized device parameters might enable the best possible thermal stability along with higher power output.

Solar photovoltaics researchers have devoted enough time to improve the performance of various types of high efficiency crystalline silicon based solar cells including passivated emitter rear cells, hetrojunction with intrinsic thin-layer solar cells, interdigitated back contact solar cells, heterojunction with interdigitated back contact solar cells and tunnel oxide passivated contact solar cells. Out of these various high efficiency solar cells, tunnel oxide passivated contact (TOPCon) solar cells are gaining more interests due to possessing various advantages such as availability of raw material, easy process sequence, high efficiency potential etc. In this review article, we shall discuss the evolutionary development of this high efficiency TOPCon solar cell, the progress made by the researchers in various aspects to improve the cell efficiency, current status of commercialization and finally future scopes of works with possible challenges.

The basics of dopant-free materials used as carrier-selective layers at the surfaces and interfaces in c-Si or poly-Si solar cells have been reviewed. Emphasis has been given to the discussion of a host of transition metal oxides (TMOs) having wide range of band structures and which have the carrier selective property of allowing only one type of carrier (electron or hole) to flow across their junctions with Si. The fabrication process of these materials are benign and at low temperatures which make them gradually attractive over the doped Si layers which need toxic materials and/or high temperatures for their formation. Silicon solar cells having dopant-free carrier selective TMOs fabricated by various groups using different fabrication processes and different contact configurations (Full area contacts, Partial area contacts or Interdigitated back contacts) have been reviewed and presented alongwith their photovoltaic performance. Different passivation schemes (full area or partial area) that could be used alongwith these dopant-free carrier selective materials have also been discussed.

The performance of a TOPCon solar cell depends on the properties of the dielectric material through which tunneling takes place. Common dielectric material used with n-type Si wafer is SiO2 due to its excellent passivation property for n-Si interface. Required thickness of SiO2 is ≈1.5 nm, making its fabrication quite challenging. Moreover, recently p-type TOPCon solar cell has been proposed as an alternative to p-type PERC (p-PRC) structure. So, a dielectric material different from SiO2 may act as a better tunneling cum passivation layer for p-Si wafer. In this paper, various alternative tunneling/passivating dielectric layers like Si3N4, Al2O3, HfO2 and ZrO2 have been discussed. The cell performances as well as the critical dielectric thicknesses of all these materials have been simulated using the three-dimensional Sentaurus TCAD software. It has been found that the critical dielectric thickness for optimum cell performances depends strongly on the tunneling effective mass of the majority carriers, dielectric barrier at the dielectric/Si interface for the majority carriers and fixed charges in the dielectric. We have also used the simulation for an arbitrary generic dielectric and studied the dependence of its critical thickness (tcritical) on the three parameters mentioned above.

Pseudostoichiometric molybdenum oxide (MoOx) thin films were deposited on glass substrates using radio frequency magnetron sputtering from sintered molybdenum trioxide (MoO3) target at relatively low substrate temperature in inert (Ar) atmosphere. Structural, morphological, and electrical properties of the deposited films were studied thoroughly, followed by detailed investigations on the sensing performance of the same toward two hazardous and toxic gases, hydrogen sulfide (H2S) and carbon monoxide (CO); specifically at low operating temperature and with low concentrations. Good response percentages with satisfactory response and recovery time were obtained for both the gases. These might be attributed to the presence of oxygen deficient and well distributed nanostructures on the surface of the film that facilitate gas adsorption/anchoring and promotes the charge transfer reactions on the surface of the semiconductor. Furthermore, extensive sensing measurements and post-sensing structural characterization were carried out, which revealed long-term stability of the sensing platform.

In this contribution, influence of dry bands on electric field distribution on a polymeric insulating surface has been carried out using Finite Element Method. Formation of dry bands on insulating surfaces result in electric field enhancement leading to surface discharges, dry-band arcing etc. which in turn affects the long term performance of the insulators. Hence, in the present work, a polymeric insulating surface is modeled as sheath model using Comsol Multiphysics software. Electric stress analysis is performed in presence of dry bands of different length and at different locations on a contaminated insulating surface. Moreover, the effect of different contamination levels on electric field distribution in presence of dry bands have also been investigated.