Orthogonal Thin Film Photovoltaics on Vertical Nanostructures

Abstract

Decoupling paths of carrier collection and illumination within photovoltaic devices is one promising approach for improving their efficiency by simultaneously increasing light absorption and carrier collection efficiency. Orthogonal photovoltaic devices are core-shell type structures consisting of thin film photovoltaic stack on vertical nanopillar scaffolds. These types of devices allow charge collection to take place in the radial direction, perpendicular to the path of light in the vertical direction. This approach addresses the inherently high recombination rate of disordered thin films, by allowing semiconductor films with minimal thicknesses to be used in photovoltaic devices, without performance degradation associated with incomplete light absorption. This work considers effects which influence the performance of orthogonal photovoltaic devices. Illumination non-uniformity as light travels across the depth of the pillars, electric field enhancement due to the nanoscale size and shape of the pillars, and series resistance due to the additional surface structure created through the use of pillars are considered. All of these effects influence the operation of orthogonal solar cells and should be considered in the design of vertically nanostructured orthogonal photovoltaics.

Electrodeposition Conditions Effect Sb2Se3 Thin‐Film Properties

“…This effect on the photocurrent may be related to the film thickness because the other properties such as phase-purity, composition, and band gap were not affected. [34] However, this film is thinner than the absorption depth, reaching lower indices of light absorption and promoting a decrease in its photocurrent [35] compared to the IC-film, for example. [33] This can be the cause of the decrease in its photocurrent compared to the IC-film.…”

“…Using a similar argument, the D-film was thinner than the others, showing lower series resistance which facilitated the charge collection of the minority carriers. [34] However, this film is thinner than the absorption depth, reaching lower indices of light absorption and promoting a decrease in its photocurrent [35] compared to the IC-film, for example. Another interesting feature is that the D-film showed more stable photocurrent transients during the same time interval, whereas the photocurrent of the IC-film quickly decreases and reaches the same intensity presented by the other films (Figure 2c).…”

Lateral Dye‐Sensitized Microscale Solar Cells via Femtosecond Laser Patterning

“…Conventional DSSCs have a sandwiched structure in which charge transport occurs perpendicular to the device surface, as shown in Figure a. Recently, solar cells with lateral structures have caught much attention owing to the following advantages in comparison with the conventional vertical structure: (a) The necessity of the transparency of the electrode can be eliminated; both electrodes can be placed at the back side and use high‐conductivity materials, while the light can be incident from the front. As a result, transmission loss can be reduced and the charge collection increased simultaneously.…”

“…Lateral DSSC is not an exception, with η less than 1% . One of the common issues of these low‐efficiency lateral solar cells is their low fill factor (FF) of less than 0.3 . It indicates that the fundamental problem of great internal loss in these lateral structures is still hard to overcome.…”

“…In comparison with previous work on lateral DSSC in Reference , the performance of this lateral DSSC is significantly improved. Its performance is also much greater than that of other types of lateral solar cells, where low levels of FF limited the overall performance of the devices. The much improved FF in this lateral DSSC overcame most internal loss of the photovoltaic process and accounted for the great improvement in η .…”