This study is a follow up to our previously published manuscript on "improved power conversion efficiency in Perovskite solar cell using silver nanoparticles modified photoanode". Three more photoanodes were fabricated which are: Ag@ P 4 VP NPs mixed with perovskite layer (S2), Ag@P 4 VP NPs simultaneously mixed both in TiO 2 and perovskite films (S3) and P25 NP simultaneously mixed both in TiO 2 and perovskite absorber (S4) and their performances were investigated systematically. The performance, especially the photocurrent, and open circuit voltage of PSCs made of Ag@P 4 VP NPs were significantly affected. The champion device is S3, which shows enhancement in power conversion efficiency (PCE) from 3.80 to 9.05%, short circuit current density (Jsc) from 11.04 to 15.87 mA cm −2 , open circuit voltage (Voc) from 0.85 to 0.88 and fill factor (FF) from 0.41 to 0.65, which demonstrates ~ 2.38 times improvement in PCE over the control device (C). When Ag@P 4 VP NPs was mixed with TiO 2 , PCE of 5.69%, Jsc of 12.61 mA cm −2 , Voc of 0.88 V and FF of 0.51 were achieved, which shows ~ 1.50 times improvement over the performance of the reference cell. Also, when Ag@P 4 VP NPs was mixed with the perovskite layer, PCE of 8.08%, Jsc of 14.18 mA cm −2 , Voc of 0.89 V and FF of 0.64 were achieved, which shows ~ 2.13 times improvement over the performance of the pristine device. The addition of Ag@P 4 VP NPs enhanced exciton generation and dissociation, encouraging charge separation/transfer, as well as reducing quenching losses. For the hysteresis test, it was found that the devices with Ag@P 4 VP NPs have almost identical J-V curves with negligible hysteresis, which is attributed to the significant reduction of the trap density of the perovskite film when Ag@P 4 VP NPs is incorporated to fill the pores with high trapping rate. We however observed hysteretic behavior in devices C and S4, which makes it difficult to estimate the real PCE.

The hole transporting material (HTM) is responsible for selectively transporting holes and blocking electrons which also plays a crucial role in the efficiency and stability of perovskite solar cells (PSCs). Spiro-MeOTAD is the most popular material, which is expensive and can be easily affected by moisture content. There is a need to find an alternative HTM with sufficiently high resistance to moisture content. In this paper, the influence of some parameters with cuprous oxide (Cu2O) as HTM was investigated using a solar cell capacitance simulator (SCAPS). These include the influence of doping concentration and thickness of the absorber layer, the effect of thickness of ETM and HTM as well as electron affinities of ETM and HTM on the performance of the PSCs. From the obtained results, it was found that the concentration of dopant in the absorber layer, the thickness of ETM and HTM and the electron affinity of HTM and ETM affect the performance of the solar cell. The cell performance improves greatly with the reduction of ETM electron affinity and its thickness. Upon optimization of parameters, power conversion efficiency for this device was found to be 20.42% with a current density of 22.26 mAcm-2, voltage of 1.12 V, and fill factor of 82.20%. The optimized device demonstrates an enhancement of 58.80%, 2.25%, 20.40% and 30.23% in PCE, Jsc, FF, and Voc over the initial cell. The results show that Cu2O in lead-based PSC as HTM is an efficient system and an alternative to spiro-MeOTAD.

This research paper is on Density Functional Theory (DFT) within Local Density Approximation. The calculation was performed using Fritz Haber Institute Ab-initio Molecular Simulations (FHI-AIMS) code based on numerical atomic-centered orbital basis sets. The electronic band structure, total density of state (DOS) and band gap energy were calculated for Gallium-Arsenide and Aluminium-Arsenide in diamond structures. The result of minimum total energy and computational time obtained from the experimental lattice constant 5.63 A for both Gallium Arsenide and Aluminium Arsenide is −114,915.7903 eV and 64.989 s, respectively. The electronic band structure analysis shows that Aluminium-Arsenide is an indirect band gap semiconductor while Gallium-Arsenide is a direct band gap semiconductor. The energy gap results obtained for GaAs is 0.37 eV and AlAs is 1.42 eV. The band gap in GaAs observed is very small when compared to AlAs. This indicates that GaAs can exhibit high transport property of the electron in the semiconductor which makes it suitable for optoelectronics devices while the wider band gap of AlAs indicates their potentials can be used in high temperature and strong electric fields device applications. The results reveal a good agreement within reasonable acceptable errors when compared with the theoretical and experimental values obtained in the work of Federico and Yin wang [1] [2].

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Dye-sensitized solar cell (DSSC) was fabricated using natural dye extracted from Roselle flower. The sensitization performance related to interaction between the dye and titanium dioxide (TiO 2 ) surface was evaluated under 100 mWcm -2 light intensity. The DSSC based on the Hibiscus sabdariffa organic dye gave a short-circuit current density (J sc ) of 0.0259 mAcm -2, open-circuit voltage (V oc ) of 0.432 V and fill factor (FF) of 0.594, yielding an overall solar conversion efficiency (η) of 0.0067%. The result obtained shows some improvement over similar studies carried out by Adenike et al. [1] with lower efficiency of 0.002%. The improved performance might be attributed to the differences in concentrations of phytoconstituents in different parts of the plant and also the type of solvent used to extract the sensitizer.