Compositional Characterization of Organo-Lead tri-Halide Perovskite Solar Cells

Perovskite photovoltaics is one of the fastest growing research fields in materials science. Apart from photovoltaics, a wide range of energy-related research fields have gained substan-tial new momentum owing to the fantastic optoelectronic properties of hybrid lead halide per-ovskites. Starting with solar cells showing a mere 3% power conversion efficiency in 2009, researchers have been able to increase this value to over 22% in 2017, comparable to the best monocrystalline silicon solar cells. These improvements are chiefly due to the compositional tuning and mixing of the ABX3 perovskite structure. However, this strategy increases not only the efficiency but also in the same time the complexity of the perovskite formulation. Differ-ent phases, from the nano- to macroscale, can potentially form. In order to rationalize the effi-ciency progress, one needs to understand and characterize the complex perovskite composi-tion and crystal structure in great detail. The main focus of this thesis lies in the in-depth compositional and phase analysis of perovskite thin films as well as full perovskite solar cells, trying to rationalize the consequences of A cation and X anion tuning and mixing. In the first part, it is shown that fabricating solar cells from a non-stoichiometric perovskite precursor composition, namely one with PbI2 excess, leads to increased grain size, enhanced cristallinity, reduced recombination as well as an improved TiO2/perovskite interface. As op-posed to lead iodide phases resulting from film degradation, which is hampering device per-formance, unreacted excess PbI2 phases originating from an excess of PbI2 in the precursor solution are very beneficial for the final solar cell efficiency, reproducibility and stability. The next scientific challenge adressed in this thesis is related to the nano- and microscale composition of the record-breaking mixed cation/mixed anion perovskite composition. Mac-roscale investigations have previously suggested that this formulation results in a single ho-mogenous phase. However, using nanoscale elemental and charge carrier distribution mapping as well as microscale structural and optical film analysis, it is here found that in high efficient solar cells partial phase segregation does take place at the micro- and nanoscale. Moreover, it is shown that mixed cation/anion formulations allow the formation of never re-ported 3D hexagonal lead halide perovskite polytypes, namely 4H and 6H. These polytypes are shown to play a key role during the crystallization process, which is also revealed for the first time here. Indeed, mixed cation/mixed anion perovskite films are fabricated via the crys-tallization sequence 2Hï 4Hï 6Hï 3R(3C). It is demonstrated that the complex crystalliza-tion via these defect-prone hexagonal intermediates can be by-passed by the incorporaton of low amounts of Cs+ cations into the structure. This can explain the improved stability as well as the increased power conversion efficiency and device reproducibility. It gives for the first time a rational explanation as to why the halide perovskite community rapidly adopted the incorporation of Cs+ in mixed perovskites. The last results presented in this thesis are related to the hole-transporting materials (HTM) used in perovskite solar cells. It is shown that carbazole-based small molecule HTMs are a cheap and efficient alternative to the much costlier commercial spiro-OMeTAD

HUBUNGAN KELELAHAN KERJA DENGAN KECELAKAAN KERJA PADA PEKERJA DI PT. PERTAMINA GEOTHERMAL ENERGY AREA LAHENDONG KOTA TOMOHON

Kecelakaan kerja merupakan suatu peristiwa tidak diharapkan tetapi tidak terjadi kebetulan melainkan ada penyebabnya. Faktor yang menyebabkan kecelakaan kerja ada dua yaitu faktor manusia dan faktor lingkungan. Kelelahan merupakan salah satu faktor manusia penyebab kejadian kecelakaan kerja. Tujuan dilakukannya penelitian ini yakni untuk mengetahui hubungan kelelahan kerja dengan kecelakaan kerja pada pekerja di PT. Pertamina Geothermal Energy Area Lahendong. Jenis penelitian menggunakan survei analitik dengan desain cross sectional. Populasi dalam penelitian ini berjumlah 60 pekerja lapangan dari bagian HSSE, maintenance dan operation, dengan sampel ditentukan dengan menggunakan teknik total sampling. Penelitian ini dilaksanakan pada Juni - November 2022. Instrumen yang digunakan yaitu kuesioner kecelakaan kerja serta Kuesioner Alat Ukur Perasaan Kelelahan Kerja (KAUPK2). Analisis data menggunakan analisis univariat dan analisis bivariat. Hasil penelitian diperoleh dengan uji statistik yaitu nilai p = 0.348 (p > 0.05), artinya kelelahan kerja tidak berhubungan dengan kecelakaan kerja pada pekerja di PT. Pertamina Geothermal Energy Area Lahendong Kota Tomohon. Hal ini karena faktor penyebab kecelakaan kerja di PT. Pertamina Geothermal Energy Area Lahendong bukan diakibatkan oleh kelelahan kerja melainkan dari faktor lain yaitu pekerja yang kurang hati-hati dan kurang teliti dalam bekerja, alat pelindung diri (APD) tidak digunakan saat bekerja serta kecelakaan yang disebabkan oleh mesin

APLIKASI PENCARIAN KONTRAKAN DAN KOS BERBASIS WEB

Aplikasi Pencarian Kontrakan dan kos adalah sebuah platform digital yang dirancang untuk membantu pengguna mencari kontrakan dan kost secara efisien.Aplikasi ini menyediakan fitur pencarian yang canggih dan informatif untuk membantu pengguna menemukan kost atau kontrakan yang sesuai dengan preferensi mereka.Dengan menggunakan algoritma pencocokan yang cerdas,aplikasi ini menghubungkan pengguna dengan daftar kontrakan yang relevan,berdasarkan kriteria yang diinginkan seperti lokasi,harga,ukuran,fasilitas ,dan lain-lain.Pengguna dapat melihat informasi rinci tentang setiap kontrakan,termasuk foto,deskripsi,dan fasilitas yang tersedia.Aplikasi ini juga menyediakan fitur peta interaktif yang memudahkan pengguna dalam menemukan lokasi kontrakan dan kos.Dengan adanya Aplikasi pencarian kontrakan kos ini diharapkan pengguna dapat mencari   kontrakan dan kos dengan lebih efisien,menghemat waktu,dan mendapatkan informasi yang akurat sehingga dapat membuat keputusan yang tepat dalam memilihkan kontrakan yang sesuai dengan kebutuhan mereka.   &nbsp

High-Efficiency Perovskite Solar Cells using Molecularly-Engineered, Thiophene-Rich,Hole-Transporting Materials: Influence of Alkyl Chain Length on Power Conversion Efficiency

The synthesis and characterization of a series of novel small-molecule hole-transporting materials (HTMs) based on an anthra[1,2-b:4,3-b′:5,6-b′′:8,7-b′′′]tetrathiophene (ATT) core are reported. The new compounds follow an easy synthetic route and have no need of expensive purification steps. The novel HTMs were tested in perovskite solar cells (PSCs) and power conversion efficiencies (PCE) of up to 18.1 % under 1 sun irradiation were 2 measured. This value is comparable with the 17.8 % efficiency obtained using spiroOMeTAD as a reference compound. Similarly, a significant quenching of the Photoluminescence in the first nanosecond is observed, indicative of effective hole transfer.Additionally, the influence of introducing aliphatic alkyl chains acting as solubilizers on the device performance of the ATT molecules is investigated. Replacing the methoxy groups on the triarylamine sites by butoxy-, hexoxy- or decoxy-substituents greatly improved the solubility of the compounds without changing the energy levels, yet at the same time significantly decreasing the conductivity as well as the PCE, 17.3 % for ATT-OBu, 15.7 % for ATT-OHex and 9.7 % for ATT-ODec

Small molecule hole transporting material for optoelectronic and photoelectrochemical devices

The present invention relates to a compound of formula (I) based on carbazole substituted by diphenylamine and used as organic hole conductors or hole transporting material in a optoelectronic or photoelectrochemical device. (I), D being being selected from formula (1) or (2)

Toward Higher Photovoltage: Effect of Blocking Layer on Cobalt Bipyridine Pyrazole Complexes as Redox Shuttle for Dye-Sensitized Solar Cells

Fluorine-doped tin-oxide (FTO) transparent conducting substrates, for use in cobalt bis(bipyridine pyrazole) complex based dye-sensitized solar cells (DSCs), were compared using the conventional TiCl4 treatment with conformal TiO2 blocking layers formed by atomic layer deposition (ALD). The conformal blocking layer prepared by ALD promotes a decrease in the dark current, owing to retarded recombination between the FTO and the cobalt electrolyte. The thickness for the conformal blocking layer was optimized to attain the best photovoltaic performance. Optimized photovoltaic devices employing a double layer provided the best results, and a peak power conversion efficiency of 10.6% was achieved under full sun light intensity