Single and double junction solar cells with high open circuit voltage were fabricated using poly{thiophene-2,5-diyl-alt-[5,6-bis(dodecyloxy)benzo[c][1,2,5]thiadiazole]-4,7-diyl} (PBT-T1) blended with fullerene derivatives in different weight ratios. The role of fullerene loading on structural and morphological changes was investigated using atomic force microscopy (AFM) and X-ray diffraction (XRD). The XRD and AFM measurements showed that a higher fullerene mixing ratio led to breaking of inter-chain packing and hence resulted in smaller disordered polymer domains. When the PBT-T1:PC₆₀BM weight ratio was 1 : 1, the polymer retained its structural order; however, large aggregated domains formed, leading to poor device performance due to low fill factor and short circuit current density. When the ratio was increased to 1 : 2 and then 1 : 3, smaller amorphous domains were observed, which improved photovoltaic performance. The 1 : 2 blending ratio was optimal due to adequate charge transport pathways giving rise to moderate short circuit current density and fill factor. Adding 1,8-diiodooctane (DIO) additive into the 1 : 2 blend films further improved both the short circuit current density and fill factor, leading to an increased efficiency to 4.5% with PC₆₀BM and 5.65% with PC₇₀BM. These single junction solar cells exhibited a high open circuit voltage at ∼0.9 V. Photo-charge extraction by linearly increasing voltage (Photo-CELIV) measurements showed the highest charge carrier mobility in the 1 : 2 film among the three ratios, which was further enhanced by introducing the DIO. The Photo-CELIV measurements with varying delay times showed significantly higher extracted charge carrier density for cells processed with DIO. Tandem devices using P3HT:IC₆₀BA as bottom cell and PBT-T1:PC₆₀BM as top cell exhibited a high open circuit voltage of 1.62 V with 5.2% power conversion efficiency.

Non invasive continuous blood pressure measurement system is more useful than conventional blood pressure measurement systems. The arterial system is extraordinarily well regulated blood delivery network in human body. It responds very quickly according to the body movements like altered body position, or in sudden excitation. So now a day's continuous blood pressure monitoring devices are becoming more essential. Many types of blood pressure measurement devices are available. Those devices allow only few blood pressure readings in every 10 minutes. In contrast to them, we develop a very low cost noninvasive continuous blood pressure measurement and monitoring system. It measures blood pressure using volume oscillometric method and photoplethysmography technique during a long time period continuously. The rate of change of blood volume in an organ such as finger has a linear relationship with blood pressure. This rate of change of blood volume in finger is measured by an optical sensor network which estimates blood pressure. It displays the numerical value of systolic and diastolic blood pressure in a mini LCD. Our developed system is reliable, accurate and less expensive.