Suppressed Formation of Conductive Phases in One-Pot Electrodeposited CuInSe₂ by Tuning Se Concentration in Aqueous Electrolyte

Abstract

The single-bath electrochemical deposition of CuInSe2 often leads to short-circuit behavior of the resulting solar cells due to the high shunt conductance. In this study, in an attempt to resolve this problem, the influence of the Se precursor concentration (CSe) on electrodeposited CuInSe2 films and solar cell devices is examined in the CSe range of 4.8 to 12.0 mM in selenite-based aqueous solutions containing Cu and In chlorides along with sulfamic acid (H3NSO3) and potassium hydrogen phthalate (C8H5KO4) additives. As CSe increases, the CuInSe2 layers become porous, and the grain growth of the CuInSe2 phase is restricted, while the parasitic shunting problem was markedly alleviated, as unambiguously demonstrated by measurements of the local current distribution. Due to these ambivalent influences, an optimal value of CSe that achieves the best quality of the films for high-efficiency solar cells is identified. Thus, the device prepared with 5.2 mM Se exhibits a power-conversion efficiency exceeding 10% with greatly improved device parameters, such as the shunt conductance and the reverse saturation current. The rationale of the present approach along with the physicochemical origin of its conspicuous impact on the resulting devices is discussed in conjunction with the electro-crystallization mechanism of the CuInSe2 compound.

Mechanochemically Synthesized SnS Nanocrystals: Impact of Nonstoichiometry on Phase Purity and Solar Cell Performance

“…Despite the higher PCE level of CIGS solar cells than that of Si cells on a laboratory scale, their commercialization has not been as successful as that of Si-based cells, which is regarded as partly due to the higher cost per unit power generation. In this regard, the need for the development of cost-effective nonvacuum processes has been recognized. − In addition, inexpensive, earth-abundant, and nontoxic new photovoltaic (PV) materials have received a considerable amount of interest as potential candidates to replace indium and gallium in CIGS. In recent years, headed by Cu 2 ZnSnS 4 (CZTS) and related quaternary semiconducting compounds, CuSbS 2 , , FeS 2 , − Fe 2 GeS 4 , , and SnS , compounds have been studied as alternative PV materials to CIGS.…”