Showing papers by "Muhammad Hassan Sayyad published in 2020"
TL;DR: In this paper, the lead-free metal halide perovskites with analogous optical and photovoltaic performances have been investigated and the role of different cations and their composition on device performances and stability has been involved and discussed.
Abstract: Since its invention in 2009, Perovskite solar cells (PSCs) has attracted great attention because of its low cost, numerous options of efficiency enhancement, ease of manufacturing and high-performance. Within a short span of time, the PSC has already outperformed thin-film and multicrystalline silicon solar cells. A current certified efficiency of 25.2% demonstrates that it has the potential to replace its forerunner generations. However, to commercialize PSCs, some problems need to be addressed. The toxic nature of lead which is the major component of light absorbing layer, and inherited stability issues of fabricated devices are the major hurdles in the industrialization of this technology. Therefore, new researching areas focus on the lead-free metal halide perovskites with analogous optical and photovoltaic performances. Tin being nontoxic and as one of group IV(A) elements, is considered as the most suitable alternate for lead because of their similarities in chemical properties. Efficiencies exceeding 13% have been recorded using Tin halide perovskite based devices. This review summarizes progress made so far in this field, mainly focusing on the stability and photovoltaic performances. Role of different cations and their composition on device performances and stability have been involved and discussed. With a considerable room for enhancement of both efficiency and device stability, different optimized strategies reported so far have also been presented. Finally, the future developing trends and prospects of the PSCs are analyzed and forecasted.
30 citations
TL;DR: In this article, a hole-transport-material-free (HTM-free) carbon-counter-electrode-based perovskite solar cells (PSCs) were analyzed using current density-voltage and impedance spectra measurements.
Abstract: Due to the tremendous increase in power conversion efficiency (PCE) of organic–inorganic perovskite solar cells (PSCs), this technology has attracted much attention. Despite being the fastest-growing photovoltaic technology to date, bottlenecks such as current density–voltage (J–V) hysteresis have significantly limited further development. Current density measurements performed with different sweep scan speeds exhibit hysteresis and the photovoltaic parameters extracted from the current density–voltage measurements for both scan directions become questionable. A current density–voltage measurement protocol needs to be established which can be used to achieve reproducible results and to compare devices made in different laboratories. In this work, we report a hysteresis analysis of a hole-transport-material-free (HTM-free) carbon-counter-electrode-based PSC conducted by current density–voltage and impedance spectra measurements. The effect of sweep scan direction and time delay was examined on the J–V characteristics of the device. The hysteresis was observed to be strongly sweep scan direction and time delay dependent and decreased as the delay increased. The J–V analysis conducted in the reverse sweep scan direction at a lower sweep time delay of 0.2 s revealed very large increases in the short circuit current density and the power conversion efficiency of 57.7% and 56.1%, respectively, compared with the values obtained during the forward scan under the same conditions. Impedance spectroscopy (IS) investigations were carried out and the effects of sweep scan speed, time delay, and frequency were analyzed. The hysteresis was observed to be strongly sweep scan direction, sweep time delay, and frequency dependent. The correlation between J–V and IS data is provided. The wealth of photovoltaic and impendence spectroscopic data reported in this work on the hysteresis study of the HTM-free PSC may help in establishing a current density–voltage measurement protocol, identifying components and interfaces causing the hysteresis, and modeling of PSCs, eventually benefiting device performance and long-term stability.
14 citations
TL;DR: A flexible printable thermoelectric generator (TEG) with both n-type and p-type organic composites of reduced graphene oxide, carbon nanotubes, poly(3,4-ethylenedixoythiphene)-polystyrene sulfate, and lead sulfide composite materials was developed in this article.
Abstract: Thermoelectric energy harvesting is one of the keystones of modern green renewable energy generation. Unfortunately, most conventional state-of-the-art inorganic semiconductor thermoelectric generators are expensive, fragile, and not flexible. Considering these limitations, we developed a flexible printable thermoelectric generator (TEG) with both n-type and p-type organic composites of reduced graphene oxide, carbon nanotubes, poly(3,4-ethylenedixoythiphene)–polystyrene sulfate, and lead sulfide composite materials. We constructed a TEG of ten alternating n–p pairs as a prototype with an effective area of 1.4 cm2 each, which generated 13 mV thermovoltage at operating temperature difference of 77 °C. It demonstrates that its fabrication is scalable, printable, and relatively simple, and the resultant structure is flexible, conformal, and reconfigurable.
10 citations
TL;DR: In this paper, the authors reported on the thin film characterization of a synthesized small molecular semiconductor N-butyl-N′-(6-hydroxyhexyl) perylene-3,4,9,10-tetracarboxylic acid diimide (N-BuHHPDI) and its potential use in Ag/N-BHPDI/PEDOT:PSS/p-Si heterojunction device.
Abstract: This paper reports on the thin film characterization of a synthesized small molecular semiconductor N-butyl-N′-(6-hydroxyhexyl) perylene-3,4,9,10-tetracarboxylic acid diimide (N-BuHHPDI) and its potential use in Ag/N-BuHHPDI/PEDOT:PSS/p-Si heterojunction device. The device is fabricated using spin coating of a conducting polymer PEDOT:PSS on p-Si substrate followed by thermal deposition of a 100-nm-thin layer of N-BuHHPDI. To complete the fabrication of Ag/N-BuHHPDI/PEDOT:PSS/p-Si heterostructure, silver (Ag) is used as the top electrode. The device shows non-ohmic and asymmetrical current–voltage (I–V) characteristics in dark conditions at 25°C which confirm the successful formation of rectifying heterojunction. Various diode parameters such as ideality factor (n), barrier height (ϕb), series resistance (Rs) and charge carrier mobility across the interface of the heterojunction are measured from the I–V characteristics. The non-ideal behavior of the diode is correlated with the film morphology obtained by atomic force microscopy. Fourier transformed infrared spectroscopy is performed to confirm the successful preparation of N-BuHHPDI. The fluorescence lifetime (22 ns) of the N-BuHHPDI thin film is measured via fluorescence spectroscopy. Different charge conduction mechanisms including the dominant one are studied for the fabricated device.
9 citations
TL;DR: In this paper, a single crystal thiophene/phenylene co-polymer 5,5ʺʺ'-diphenyl-2,2′:5′,2ʺ:5´,2´)-sexithiophene (P6T) was reported to demonstrate high charge carriers' mobility and large photoluminescence quantum efficiency (PLQE).
1 citations
TL;DR: In this paper, the authors investigated the effects of reducing pristine graphene oxide (GO) by hydrazine monohydrate and the degree of reduction was carefully controlled by reduction time, and they found that the reduction time can increase the Seebeck coefficient and electrical conductivity of RGO.