A composition comprising an electron-donating polymer and an electron acceptor wherein the electron-donating polymer comprises a benzo[1,2-b:4,5-b′]dithiophene repeat unit and wherein a film of the electron-accepting material has a peak absorption wavelength greater than 1000 nm. The composition may be used as a photosensitive layer of an organic photodetector.

An arrangement includes a solar cell and a covering, wherein the covering covers the solar cell, at least on the side that is intended to be exposed to electromagnetic radiation of the sun. The covering has an electrochromic layer. The arrangement also has a control unit for controlling the electrochromic layer. The control unit is designed to control the transmittance of the electrochromic layer for electromagnetic radiation in a defined wavelength range by applying an electrical voltage to the electrochromic layer.

Provided is a method for preparing lead iodide, which controls the crystal form of lead iodide through temperature, including: dissolving a lead compound in a first acid solution and adding an iodine compound to form a reaction solution including the first lead iodide; and heating the reaction solution to a temperature of 60° C. or more and standing at a constant temperature, to obtain the second lead iodide, wherein a peak intensity of the (003) crystal plane of the second lead iodide is greater than or equal to a peak intensity of the (110) crystal plane. Provided is also a method for preparing the perovskite film.

Provided is a method for preparing lead iodide, which controls the crystal form of lead iodide through temperature, including: dissolving a lead compound in a first acid solution and adding an iodine compound to form a reaction solution including the first lead iodide; and heating the reaction solution to a temperature of 60° C. or more and standing at a constant temperature, to obtain the second lead iodide, wherein a peak intensity of the (003) crystal plane of the second lead iodide is greater than or equal to a peak intensity of the (110) crystal plane. Provided is also a method for preparing the perovskite film.

A solar cell system and a flexible solar panel are disclosed herein. The solar cell system includes a glass housing, a set of rows of solar cells each defining a front side and a rear side and arranged within the glass housing. The solar cell system can also include a reflective element disposed in the glass housing and facing the rear side of the set of rows of solar cells and a first terminal coupled to a first end of the set of rows of solar cells, traversing through and sealed against the first end of the glass housing. The solar cell system can be configured with other solar cell systems into the flexible solar panel that is deployable in a wide range of potential applications.

According to one embodiment of the present disclosure, a biometric sensor includes a flexible substrate, a first light-emitting part disposed on one side of the flexible substrate to output first light toward the body, a second light-emitting part disposed on one side of the flexible substrate to output second light different from the first light toward the body, an elastomer disposed on one side of the flexible substrate in a shape surrounding the first light-emitting part and the second light-emitting part, and a light-receiving part disposed on the other side of the flexible substrate to receive third light corresponding to the first light and fourth light corresponding to the second light.

A tandem photovoltaic device includes a silicon photovoltaic cell having a silicon layer, a perovskite photovoltaic cell having a perovskite layer, and an intermediate layer between a rear side of the perovskite photovoltaic cell and a front (sunward) side of the silicon photovoltaic cell. The front side of the silicon layer has a textured surface, with a peak-to-valley height of structures in the textured surface of less than 1 μm or less than 2 μm. The textured surface is planarized by the intermediate layer or a layer of the perovskite photovoltaic cell. Forming the tandem photovoltaic device includes texturing a silicon containing layer of a silicon photovoltaic cell and operatively coupling a perovskite photovoltaic cell comprising a perovskite layer to the silicon photovoltaic cell, thereby forming a tandem photovoltaic device and planarizing the textured surface of the silicon containing layer of the silicon photovoltaic cell.

A method comprised of combining

##STR00001## form a solution containing a polymer

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In this polymer R, R′, and R″ are independently selected from the group consisting of: H, Cl, F, CN, alkyl, alkoxy, alkylthio, ester, ketone and aryl groups; and X is selected from aryl groups.

An organic photovoltaic device comprises a first electrode, at least one organic heterojunction layer positioned over the first electrode, a second electrode positioned over the organic heterojunction layer, and a thin film stack positioned over the second electrode, comprising a plurality of sublayers of a first dielectric material alternating with a plurality of sublayers of a second dielectric material, wherein at least one of the plurality of sublayers of the first dielectric material has a thickness that is different from another of the plurality of sublayers of the first dielectric material, wherein the organic photovoltaic device has a mean transmittance of between 10% and 100% for light between 420 nm and 670 nm, with a variance of ±10%, and wherein an index contrast between the sublayers in the thin film stack is at least 0.1. A method of fabricating an organic photovoltaic device is also disclosed.

In one aspect, window inserts are described herein, which can modulate transmission of electromagnetic radiation through a window and can be self-powered. In some embodiments, a window insert comprises a photovoltaic device, the photovoltaic device including a photosensitive layer having peak absorption between 250 nm and 450 nm and an average transmittance of at least 50 percent in the visible region of the electromagnetic spectrum.