Colloidal quantum dot solar cells on curved and flexible substrates

Abstract

Colloidal quantum dots (CQDs) are semiconductor nanocrystals synthesized with, processed in, and deposited from the solution phase, potentially enabling low-cost, facile manufacture of solar cells. Unfortunately, CQD solar cell reports, until now, have only explored batch-processing methods—such as spin-coating—that offer limited capacity for scaling. Spray-coating could offer a means of producing uniform colloidal quantum dot films that yield high-quality devices. Here, we explore the versatility of the spray-coating method by producing CQD solar cells in a variety of previously unexplored substrate arrangements. The potential transferability of the spray-coating method to a roll-to-roll manufacturing process was tested by spray-coating the CQD active layer onto six substrates mounted on a rapidly rotating drum, yielding devices with an average power conversion efficiency of 6.7%. We further tested the manufacturability of the process by endeavoring to spray onto flexible substrates, only to find that spraying while the substrate was flexed was crucial to achieving champion performance of 7.2% without compromise to open-circuit voltage. Having deposited onto a substrate with one axis of curvature, we then built our CQD solar cells onto a spherical lens substrate having two axes of curvature resulting in a 5% efficient device. These results show that CQDs deposited using our spraying method can be integrated to large-area manufacturing processes and can be used to make solar cells on unconventional shapes.

Solution-Processed Environmentally Friendly Ag2S Colloidal Quantum Dot Solar Cells with Broad Spectral Absorption

“…In 2002, some of the device structures seen today for QDSCs were proposed [1]. Since then, different types of QDSCs have been investigated including p-i-n junction solar cells [2][3][4][5][6][7][8][9][10][11], quantum dot sensitized solar cells (QDSCs) [12][13][14][15][16], and QD-polymer solar cells [17]. State of the art PbS QDSCs achieves most of goals stated above with efficiencies currently around 11.3% [5].…”

Inorganic-ligand exchanging time effect in PbS quantum dot solar cell

“…[1][2][3][4] The solutionbased process also has provided high feasibility of realizing flexible and large scale photovoltaic devices with costeffective fabrication. [5][6][7][8] Despite these favorable characteristics, poor charge transport and imperfect surface status of CQDs hinder high photovoltaic performance compared to the theoretical conversion efficiency. During the synthetic process, CQDs are capped by long and bulky organic ligands which enable to control the size of CQDs by preventing over-size aggregation and enhancing chemical stability.…”

Advancing colloidal quantum dot photovoltaic technology

“…CQDs are a particularly promising solar cell material for several reasons. They offer the potential for the realization of low-cost devices [16,[19][20][21][22] through their ease of manufacturing [16,23,24], air stability [25][26][27] and film flexibility [28][29][30][31][32][33][34][35], thus making them compatible with roll-to-roll fabrication techniques. Though the true costs of scaling up CQD solar cell manufacturing to the gigawatt power scale are unknown, they are expected to be similar to those for organic photovoltaics [36] because of the similarities in materials, synthesis, and growth processes involved in the two technologies.…”