Tandem solar cells have higher efficiency than single-junction
devices owing to their wide photon absorption range. A wide band gap
(Eg) absorber absorbs the higher-energy photons in the
top cell. In contrast, a comparatively low band gap absorber material
is utilized in the bottom cell to absorb the filtered low-energy photons.
Consequently, thermalization and transparent energy losses are overshadowed
by the top subcell (Topsc) and the bottom subcell (Bottomsc), respectively. However, to achieve the best efficiency
from a tandem design, the choice of active material in the Topsc and the Bottomsc plays an important role. Therefore,
in this proposed study, a tandem solar cell comprising a perovskite
(Eg 1.68 eV)-based top cell and a copper indium gallium
selenide (CIGS, Eg 1.1 eV)-based Bottomsc has
been designed and analyzed. A state-of-the-art Me-4PACz ([4-(3,6-dimethyl-9H-carbazol-9-yl)butyl] phosphonic acid) hole transport layer
(HTL) in the perovskite solar cell reported in the previous literature
has been considered for the top cell, whereas a calibrated CIGS-based
Bottomsc with 16.50% efficiency is designed. Both the Topsc and the Bottomsc are examined for the tandem
configuration using filtered spectra and current-matching techniques.
In perovskite/CIGS tandem design, an ideal tunnel recombination junction
uses Me-4PACz and ITO layers. In a tandem configuration with matched
current density at an absorber thickness of 347 nm for Topsc and 2.0 μm for Bottomsc, the device delivered an
open-circuit voltage (V
OC), current density
(J
SC), and fill factor (FF) of 1.92 V,
20.04 mA/cm2, and 77%, respectively, resulting in an overall
power conversion efficiency (PCE) of 29.7%. The results reported in
this work would be beneficial for the development of perovskite-CIGS-based
monolithic tandem solar cells in the future.
The conversion efficiencies for silicon-based photovoltaic devices have become stagnant, with the record conversion efficiency of 26.7% achieved in 2017.
Perovskite quantum dots (CsPbI3-PQDs), a translucent material, have gained great interest in the PV industries owing to their unified virtues of perovskites and quantum dots. However, researchers have found that perovskite solar cell (PSCs) suffer from issues like low stability at high relative humidity, energy states imbalance, severe hysteresis, and an easy decomposition under ultraviolet (UV) radiation that severely restrict their industrialization. Quantum dots (QDs) are excellent materials with numerous admirable traits that have been extensively employed in PSCs to overcome the aforementioned problems. To achieve high performance of the examined device, the CsPbI3-PQDs has been stacked between two charge transport layers, i.e., Cl@SnO2 (to facilitate electrons towards cathode) and P3HT (to facilitate holes towards anode). In this context, study of variations in different parameters such as thickness and acceptor density of the CsPbI3-PQDs absorber layer has been done. After varying the thickness and acceptor density of the CsPbI3-PQDs layer, the cell’s performance is optimized at thickness of 400 nm and acceptor density of 1×1017/cm3 delivering higher PV parameters power conversion efficiency (PCE):16.17 %, open circuit voltage (VOC):1.02 V, short circuit density (JSC):18.06 mA/cm2 and fill factor (FF): 87.06 % respectively. Thereafter, the effects of bulk defects in CsPbI3-PQDs and the interface between CsPbI3-PQDs and Cl@SnO2 have been explored in this work. For the cell to work at its best, the bulk defect density and interface defect density, respectively, should not be more than 1×1014 /cm3 and 1×1013 /cm2. Afterwards, a comprehensive study has been done by varying the front electrode transparency (from 40% to 95%) to improve the device performance. With 95% of front electrode transparency, the performance of device is improved due to increase in the photon coupling.
Polycrystalline Silicon on Oxide (POLO) passivating contacts have emerged as a carrier selective contact for high-efficiency Si-based photovoltaic (PV) devices. In this paper, double POLO PERC (Passivated Emitter and Rear Contact) device is designed by employing POLO contacts on both contact sides to reduce the contact recombination losses through Silvaco-TCAD tool. The performance of the double POLO PERC device has been studied by using the PV parameters and current-density (J-V) curve. The impact of tunnel oxide thickness variation (1 nm, 1.25 nm, 1.5 nm) in the tunnel oxide layer is also analyzed. The performance of textured double POLO PERC solar cell is optimized at 1.5 nm thickness (TOX), which reflects optimum conversion efficiency of 25.5%. Reported study of double POLO PERC device may open up a door for further improvement in PERC device performance.
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