DEVELOPMENT OF ROLL-TO-ROLL SLOT DIE COATED PEROVSKITE SOLAR CELLS

Perovskite solar cells (PSCs) have gained a lot of attention in recent years because of their outstanding optoelectronic properties and ability to tolerate defects. Additionally, they can be produced at high throughput using solution processing techniques. It is this feature of perovskite that is leveraged in this work to show their scale up potential by R2R slot die coating.Slot die coating is a highly precise and controllable technique that can be used to coat a wide range of materials onto a variety of substrates, including flexible and rigid materials. Slot die coating is commonly used in the production of electronic devices, solar cells, and other products that require thin, uniform films of materials. First a P-I-N architecture of PSCs was developed and optimised with 4 layers slot die coated. This included the hole transport layer (PEDOT:PSS), active layer (MAPbI3), electron transport layer (PCBM), buffer layer (BCP). With 4 R2R slot die coated layer, a stabilised PCE of 12% is achieved. Further, a low toxic solvent system was used to coat the MAPbI3 and its economic benefits are discussed. Next, in efforts to replace PEDOT:PSS, PTAA hole transport layer was explored. Due to thin coating of PTAA on rough surfaces of PET-ITO, PTAA based devices resulted in high shorting. To avoid this a thin buffer layer of PEDOT:PSS on PET-ITO was slot die coated before coating PTAA. This improved the performance of the PSCs to 15.2%. Further, the role of PEDOT:PSS is characterised using AFM and XPS. Additionally, the optimization of a R2R slot die coating process for MAPbI3 was carried out on a PTAA surface. The loss of performance that occurred during the transfer from spin coating to R2R slot die coating was characterized, and multiple theories were tested to understand the cause. It was found that the poor interface between MAPbI3 and PTAA was responsible for the drop in performance. Finally, the addition of dimethyl sulfoxide (DMSO) helped to reduce the gap in performance between R2R and spin-coated MAPbI3 on PTAA hole transport layers. The presence of DMSO slowed the growth of crystal formation, leading to improved crystal orientation and improved performance of the PSCs

A Cross-Sectional Study on Knowledge and Use of Contraception in Damoh District, Madhya Pradesh, India

Ensuring universal access to sexual and reproductive health (SRH) is one of the 17 Sustainable Development Goals (SDGs) to be achieved by 2030, adopted by the United Nations. Women’s improved reproductive health is positively associated with their knowledge and adoption of contraceptives. Contraception is crucial in determining the family size, birth interval, and women's health and falls under SDG3 and SDG5. This study aimed to highlight the knowledge and use of contraceptives in the Damoh district located in  Madhya Pradesh, India. We utilised primary data collected through a personal survey using a structured Interview Schedule from eight sampling units in the district. For this, we employed descriptive statistics and regression techniques for the analysis. Results reveal that a substantial share of women had knowledge of at least a single method of contraception. However, female sterilisation and pills were the most commonly known methods for women. Nonetheless, the knowledge of contraception was not found to be reflected in the adoption as nearly one-third of all women were not using any method of contraception. Further, the level of adoption of different contraceptive methods varied across socio-demographic backgrounds. Therefore, emphasis on information, education and communication (IEC) initiatives may lead to an increase in the adoption of modern contraceptives

Predicting Low Toxicity and Scalable Solvent Systems for High‐Speed Roll‐to‐Roll Perovskite Manufacturing

Printed lead‐based perovskite photovoltaics (PV) have gained interest due to their potential to be manufactured with scalable roll‐to‐roll techniques. In industrial scale‐up, toxicity of inks can constrain roll‐to‐roll manufacturing due to the added cost of managing toxic effluents. Due to solvent toxicity, few perovskite solution chemistries in published works are scalable to gigawatt production capacity at low cost. Herein, it is shown that for scalable PV production, the use of aprotic polar solvents should be avoided due to their overall toxicity. Compliance with worldwide worker safety regulations for solvent exposure limits could require additional air handling requirements for some solvents, which in turn would affect cost‐effectiveness. It is shown that costs associated with handling of hazardous substances can be significant and estimate an added cost of ¢3.7/W for dimethylformamide (DMF)‐based inks. To solve this problem, a new perovskite ink solvent system is developed that is composed entirely of ether and alcohol, which has an effective exposure limit 14× higher than DMF, making it suitable for industrial coating processes. It is shown that the new ink solvent system is capable of fabricating high‐efficiency perovskite solar cells processed in 1 min on a standard roll‐to‐roll system

Predicting a process window for the roll-to-roll deposition of solvent-engineered SnO2 in perovskite solar cells

Lightweight flexible perovskite solar cells (PSCs) offer advantages over rigid solar cells including power to weight, variety of form factor and ability to scale. With breakthroughs in the power conversion efficiency (PCE) of PSCs, scaling up PSCs with similar performance has become a topic of interest. Roll-to-roll (R2R) manufacturing is one promising method to leverage the low temperature processing ability of PSCs. In this work, we demonstrate the R2R slot-die coating of the SnO2 electron transport layer, applying the low flow limit to showcase its pertinence in assessing the coating window for slot-die coating. It was observed that low flow limit can accurately predict the processing window for solvent-engineered SnO2 solutions streamlining scale up from benchtop to full R2R coating. We achieved a PCE of 16.35% for R2R-coated SnO2-based MAPbI3 perovskite devices exceeding the performance of benchtop-coated devices

Sustainable solvent selection for the manufacture of methylammonium lead triiodide (MAPbI3) perovskite solar cells

Perovskite solar cells have emerged as a promising and highly efficient solar technology. Despite efficiencies continuing to climb, the prospect of industrial manufacture is hampered by concerns regarding the safety and sustainability of the solvents used in lab scale manufacture. In this paper, we aim to present a methodology for green solvent selection informed by EHS considerations from the Chem-21 guide for succesful methylammonium lead triiodide (MAPbI3) precursor dissolution. Through the use of this methodology we present a N,N-dimethylformamide (DMF)-free alternative solvent system for deposition of MAPbI3 precursors (MAI and PbI2) consisting of dimethylsulfoxide (DMSO), dimethylpropyleneurea (DMPU), 2-methyltetrahydrofuran (2-MeTHF) and ethanol (EtOH). We have investigated 3 candidate solutions with slightly different compositions of these four solvents, all of which produce dense, uniform and pinhole-free perovskite films via spin coating. All three candidate solutions (A-C) match the average device efficiencies of the DMF/DMSO contol devices (12.4%) with Candidate A, which consists of 40% DMSO, 30 % DMPU, 20% 2-MeTHF and 10% EtOH (vol%), producing a champion PCE of 16.1% compared to 16.2% for DMF/DMSO (80/20 vol%). Perovskite films cast from the three candidate solutions show improved crystallinity, higher flourescence emission, and improved crystal size uniformity than those cast from DMF/DMSO. This work aims to: highlight the key solvent parameters which determine effective MAPbI3 precursor dissolution; provide a set of criteria for appropriate alternative solvent selection; and demonstrate the application of green chemistry principles to solvent selection for perovskite photovoltaic manufacturing

Vaginal foreign body in a child: Sexual abuse or sibling prank?

Vaginal foreign body is a rare condition. We present a 6-year-old girl who had dysuria and itching in the perineum; examination revealed a vaginal foreign body which was a broken safety pin. Radiographs after its removal revealed a pin of the safety pin left in the vagina which was later removed under anesthesia. A high index of suspicion for a vaginal foreign body should be present while evaluating a child with genitourinary complaints. Vaginal foreign body in children may be an indicator of possible sexual abuse; although in the present case, it was a prank by her elder sibling. Importance of postprocedural radiographs has been emphasized after removal as multiple/broken pieces may be present, which may not have been visualized initially. Evaluation for concurrent sexually transmitted diseases is paramount if sexual abuse is suspected

Effect of Abiotic Factors on the Population Dynamics of Red Spider Mite, Tetranychus urticae Koch. of Brinjal in Malwa Region, Madhya Pradesh, India

Field experiments were conducted to investigate the population dynamics of the red spider mite (Tetranychus urticae Koch) in brinjal and its relationship with various abiotic parameters during the 2020 and 2021 crop seasons at Patan farm, Krishi Vigyan Kendra, Mandsaur, Malwa region of Madhya Pradesh. The findings indicated that the red spider mite population initiated in the 30th and 31st standard weeks in 2020 and 2021, respectively. The peak population of mites per 2 cm2 leaf area was observed in the 43rd standard week (11.52) in 2020, while the highest population was noted in the 41st standard week (9.91) in 2021. It was evident that mite infestation was substantial during October in both years. There was a noteworthy positive correlation between the population of predatory mites, maximum temperature, and sunshine hours with the red spider mite pest, while a negative correlation was observed with relative humidity