Selenium‐Graded Sb₂(S_1−xSe_x)₃ for Planar Heterojunction Solar Cell Delivering a Certified Power Conversion Efficiency of 5.71%

Abstract

To efficiently convert solar energy into electricity at low cost with long‐term stability is one of the major tasks in solar cell research and applications. Antimony sulfide‐selenide [Sb2(S1−xSex)3] with a tunable bandgap in the range of 1.1–1.8 eV are considered promising photovoltaic materials due to their low‐toxicity, long‐term durability, and abundant element availability. Herein, selenium‐graded Sb2(S1−xSex)3 is synthesized through diffusion controlled solid‐state reaction between selenium and pre‐formed Sb2S3 film. In the device, sulfur‐rich Sb2(S1−xSex)3 with large bandgap leads to high voltage output, while narrow‐bandgap selenium‐rich Sb2(S1−xSex)3 expands spectral response toward longer wavelength. As a consequence, the device yields an open‐circuit voltage comparable to Sb2S3 solar cell, along with a significantly enhanced photocurrent density of 19.43 mA cm−2, finally delivering a certified power conversion efficiency of 5.71%, which is the highest certified value in planar heterojunction solar cells based on Sb2(S1−xSex)3. Initial stability examination shows that the device can maintain 88% efficiency after storing for 90 days in moderate humidity and ambient light irradiation. This investigation offers an effective strategy to the fabrication of composition‐graded Sb2(S1−xSex)3 for long‐term stable devices. The methodology may be extended for the fabrication of a broad class of composition‐graded metal sulfide/selenide for solar cell performance enhancement.

Review of Recent Progress in Antimony Chalcogenide‐Based Solar Cells: Materials and Devices

“…Absorber Engineering : Preliminary research proposed using coevaporation of Sb 2 S 3 and Sb 2 Se 3 to fabricate Sb 2 (S x Se 1−x ) 3 films and achieved a PCE of 4.2% for planar Sb 2 (S x Se 1−x ) 3 solar cells . Then, Chen and coworkers fabricated solution‐processed selenium‐graded Sb 2 (S x Se 1−x ) 3 films, and the planar devices delivered a certificated PCE of 5.71% with a high V OC of 0.56 V, a J SC of 19.48 mA cm −2 , and an FF of 52.3% . The complete device structure is described as FTO/c‐TiO 2 ETL/S‐rich Sb 2 (S x Se 1−x ) 3 /Se‐rich Sb 2 (S x Se 1−x ) 3 /spiro HTL/Au.…”

“…c) J–V curves of devices based on Sb 2 S 3 , Sb 2 (S 1−x Se x ) 3 and Sb 2 Se 3 , and Sb 2 (S 1−x Se x ) 3 ‐based device after storage for 90 days. Reproduced with permission . Copyright 2017, Wiley‐VCH.…”

Efficient Double Buffer Layer Sb2 (SexS1–x)3 Thin Film Solar Cell Via Single Source Evaporation

“…However, the Se‐ and S‐ based atmosphere distribution were complicated due to spatial gradient effect of double sources and the obtained film composition was not uniform. Such composition non‐uniformity produced various kinds of sub‐energy level leading to photocarrier recombination …”

Alkali Metals Doping for High‐Performance Planar Heterojunction Sb2S3 Solar Cells

“…Besides the synthesis of active materials, interfacial materials and interfacial engineering play critical roles in determining whether the high quality absorber material can finally transfer to attainable electricity. Inspired by the development of organic/inorganic hybrid solar cells, a broad range of hole transporting materials such as poly(3‐hexylthiophene), 2,2′,7,7′‐tetrakis( N , N ‐di‐ p ‐methoxyphenylamine)‐9,9′‐spirobifluorene) (Spiro‐OMeTAD) and inorganic CuSCN, V 2 O 5 , NiO x have been examined for device performance improvement.…”