The spectrum of 400 to 1100 nm sunlight can be divided into three bands, each absorbed by organic photovoltaic devices that are particularly efficient under the band in question, to achieve higher photoelectric conversion efficiency. The three bands are the absorption bands of fullerene (C70), chloroaluminum phthalocyanine (ClAlPc), and tin naphthalocyanine dichloride (SnNcCl2), which have peak values of 500, 731, and 863 nm, respectively. C70 is a well-known acceptor, whereas ClAlPc and SnNcCl2 serve as donors. In combination with another donor made of 4,4’-cyclohexylidenebis[N,N-bis(4-methylphenyl)benzenamine] (TAPC), which is almost transparent in 400 to 1100 nm, three devices were fabricated and had active layers of TAPC : C70, ClAlPc : C70, and SnNcCl2 : C70. After the doping proportions of these materials had been optimized, the maximum power conversion efficiency (PCE) values of the three devices were 4.52%, 4.3%, and 1.33%, respectively. The properties of donor material dominated the differences among these device behaviors. Subsequently, the overall PCE of a simulated multiple reflection module was calculated using these three devices, which, depending on the arranged sequence in which they were exposed to light and reflected the light to another, generated different absorption spectrum and thus influenced the overall PCE of the photovoltaic integrator. The highest overall simulated and experimental PCE of the photovoltaic integrator was 6.12% and 5.9%, respectively.
In this paper, a switchable window based on cholestreric liquid crystal (CLC) was demonstrated. Under different
applied voltages, incoming light at visible and infrared wavelengths was modulated, respectively. A mixture of CLC with
a nematic liquid crystal and a chiral dopant selectively reflected infrared light without bias, which effectively reduced the
indoor temperature under sunlight illumination. At this time, transmission at visible range was kept at high and the
windows looked transparent. With increasing the voltage to 15V, CLC changed to focal conic state and can be used as a
reflective display, a privacy window, or a screen for projector. Under a high voltage (30V), homeotropic state was
achieved. At this time, both infrared and visible light can transmit which acted as a normal window, which permitted
infrared spectrum of winter sunlight to enter the room so as to reduce the heating requirement. Such a device can be used
as a switchable window in smart buildings, green houses and windshields.