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Bifacial perovskite solar cells (Bi-PSCs) have attracted substantial attention within the photovoltaic (PV) community due to their potential for enhanced power generation, suitability for integration into building structures and applicability in multijunction PV systems. This study presents the fabrication of efficient Bi-PSCs and investigates their unique properties using various characterization techniques, including Lambertian reflection effects through tilt angle arrangements and bottom albedo illuminations. The control device achieved a maximum power conversion efficiency (PCE) of 17.46% under front-side 1 Sun AM1.5G illumination. A significant influence of ground Lambertian reflection is observed with tilt angle variations, resulting in an increase in PCE from 17.46% → 18.82% as the tilt angle reached 20°. Additionally, enhancing the rear-side albedo to 0.5 Sun yielded a maximum PCE of 26% with a bifaciality factor of ∼90% at a tilt angle of 20°. Consequently, the synergistic effect of 0.5 Sun albedo and a 20° angular light inclination led to the development of Bi-PSCs with an efficiency of 26.46%. SCAPS-1D simulations are further employed to validate the experimental Lambertian reflection effects. Moreover, the Bi-PSCs exhibited intrinsic self-encapsulation and chemical robustness (T80for 2000 h in the N2atmosphere). This study anticipates that cost-effective and highly efficient Bi-PSCs will emerge as a leading PV technology in both single-junction and tandem PV configurations for electricity generation in the near future.

Here, we systematically study the effect of fluorination on the performance of all-polymer solar cells by employing a naphthalene diimide (NDI)-based polymer acceptor with thiophene-flanked phenyl co-monomer. Fluorination of the phenyl co-monomer with either two or four fluorine units is used to create a series of acceptor polymers with either no fluorination (PNDITPhT), bifluorination (PNDITF2T), or tetrafluorination (PNDITF4T). In blends with the donor polymer PTB7-Th, fluorination results in an increase in power conversion efficiency from 3.1 to 4.6% despite a decrease in open-circuit voltage from 0.86 V (unfluorinated) to 0.78 V (tetrafluorinated). Countering this decrease in open-circuit voltage is an increase in short-circuit current from 7.7 to 11.7 mA/cm2as well as an increase in fill factor from 0.45 to 0.53. The origin of the improvement in performance with fluorination is explored using a combination of morphological, photophysical, and charge-transport studies. Interestingly, fluorination is found not to affect the ultrafast charge-generation kinetics, but instead is found to improve charge-collection yield subsequent to charge generation, linked to improved electron mobility and improved phase separation. Fluorination also leads to improved light absorption, with the blue-shifted absorption profile of the fluorinated polymers complementing the absorption profile of the low-band gap PTB7-Th.

We report on the structural, morphological and optical properties of AB(Br1–xClx)3(where, A = CH3NH3+, B = Pb2+and x= 0 to 1) perovskite semiconductor and their successful demonstration in green and blue emissive perovskite light emitting diodes at room temperature. The bandgap of perovskite thin film is tuned from 2.42 to 3.16 eV. The onset of optical absorption is dominated by excitonic effects. The coulomb field of the exciton influences the absorption at the band edge. Hence, it is necessary to explicitly account for the enhancement of the absorption through the Sommerfield factor. This enables us to correctly extract the exciton binding energy and the electronic bandgap. We also show that the lattice constant varies linearly with the fractional chlorine content satisfying Vegards law.

The energy band gaps of Pb halide perovskites are higher than the optimal band gap required for single-junction solar cells, governed by the Shockley–Queisser radiative limit. The pure Sn and Pb–Sn mixed-based perovskites have drawn significant attention due to their ability to lead to lower band gaps and open a new door for all perovskite tandem applications. There has been continuous progress toward the rapid improvement in the power conversion efficiency of Sn and Pb–Sn mixed-based perovskite solar cells (PSCs). Along with efforts for efficiency, it is worth analyzing the in-depth recombination dynamics for further development of Sn-based PSCs. The lower bimolecular recombination rate constant (k) is often attributed to the high performance of PSCs. Herein, we study the role of “B” cations in charge carrier recombination dynamics (CCRD) of ABX3(A = MA+, FA+, and Cs+; B = Pb2+, Sn2+, and X = I–)-based PSCs. We fabricated p–i–n configuration-based FA0.95Cs0.05PbI3(pure Pb), MA0.20FA0.75Cs0.05SnI3(pure Sn), and (MAPbI3)0.4(FASnI3)0.6(Pb–Sn mixed) PSCs and compared the CCRD of all the three PSCs. We optimized the Sn-based perovskite thin film (pure Sn) in terms of moisture and thermal stability in order to minimize the error due to perovskite degradation. We note that despite having lower open-circuit voltage (VOC), a pure Sn-based PSC shows lower kthan that of Pb–Sn mixed and pure Pb-based PSCs, which is a contradictory result. This slow relaxation lifetime of the charge carrier in Sn-based PSCs can be correlated with recombination through the defect states without introducing the quasi-Fermi-level splitting. Furthermore, our results suggest that the rate law of charge carrier decay has nonlinear dependence of kon nin Sn-based PSCs, whereas it is linear in the other two cases.