{"id":238291,"date":"2026-06-03T22:16:44","date_gmt":"2026-06-04T03:16:44","guid":{"rendered":"https:\/\/lifeboat.com\/blog\/2026\/06\/highly-efficient-perovskite-cigs-tandem-enabled-by-modification-of-band-profile-of-cigs-bottom-cell"},"modified":"2026-06-03T22:16:44","modified_gmt":"2026-06-04T03:16:44","slug":"highly-efficient-perovskite-cigs-tandem-enabled-by-modification-of-band-profile-of-cigs-bottom-cell","status":"publish","type":"post","link":"https:\/\/lifeboat.com\/blog\/2026\/06\/highly-efficient-perovskite-cigs-tandem-enabled-by-modification-of-band-profile-of-cigs-bottom-cell","title":{"rendered":"Highly Efficient Perovskite\/CIGS Tandem Enabled by Modification of Band Profile of CIGS Bottom Cell"},"content":{"rendered":"

<\/a><\/p>\n

This study examined the potential of narrow-bandgap (Perovskite-based tandem solar cells are a promising photovoltaic (PV) technology to exceed the Shockley\u2013Queisser limit of single-junction solar cells. Perovskite\/Si tandem solar cells have been intensively studied, demonstrating a record power conversion efficiency (PCE) of 34.6% [1<\/a>]. In contrast, the certified record PCE of perovskite\/Cu(In, Ga)Se2 (CIGS) tandem solar cells remains 24.6% with a reported efficiency of 24.9% [1<\/a>, 2<\/a>]. Theoretical calculations for double-junction tandem solar cells using a detailed balance model indicate that the bandgap (E<\/i>g<\/sub>) combinations of 1.12 eV (for a bottom cell) and 1.70 eV (for a top cell) or 0.90 to 1.04 eV (for a bottom cell) and 1.58 to 1.67 eV (for a top cell) can yield a maximum theoretical tandem efficiency [3<\/a>, 4<\/a>]. Wide-bandgap perovskite (with E<\/i>g<\/sub> equal to or greater than 1.7 eV) has been actively studied for tandem application with Si (E<\/i>g<\/sub> = 1.12 eV), the most successful solar cell technology to date as a bottom cell. However, previous studies have shown that wide-bandgap perovskite suffers from substantial open-circuit voltage (V<\/i>OC<\/sub>) loss due to halide segregation [5<\/a>], and the maximum PCEs of single-junction perovskite cells have been produced by perovskite with E<\/i>g<\/sub> between 1.52 and 1.63 eV [6<\/a>\u2013 8<\/a>]. The bandgap of CIGS can be tuned between 1.01 and 1.68 eV by adjusting the Ga\/(Ga+In) (GGI) ratio and through tuning of bandgap grading profile [9<\/a>]. Employing a narrow-bandgap CIGS close to 1.00 eV as a bottom cell is advantageous to use the most efficient, conventional bandgap perovskite as the top cell. Therefore, unlike Si, the bandgap tunability of CIGS offers an opportunity for perovskite\/CIGS to attain a greater ultimate performance than perovskite\/Si tandem solar cells. Han et al. [10<\/a>] introduced a thick indium-doped tin oxide (ITO) recombination layer to bury the intrinsic surface roughness of CIGS, followed by chemical mechanical polishing to prepare a smooth surface for the subsequent solution process of perovskite, attaining a certified PCE of 22.4%. Albrecht and coworkers have improved the PCE of perovskite\/CIGS tandem solar cells by modifying the hole transport layer (HTL). In their earlier work, a NiOx<\/sub>\/PTAA bilayer was utilized to form a uniform HTL on CIGS bottom cells. Recently, a self-assembled monolayer such as 2PACz and Me-4PACz was used, which can enhance the device performance of single-junction perovskite solar cell and its perovskite\/CIGS tandem counterpart, achieving a certified PCE of 24.2% [2<\/a>, 11 <\/a>\u2013 13<\/a>].<\/p>\n

Most recent studies on perovskite\/CIGS tandem solar cells have focused on optimizing the perovskite top cell. In contrast, all CIGS bottom cells include an absorber with a double-graded (DG) bandgap profile optimized around the bandgap of ~1.1 eV. The DG bandgap profile has been adapted primarily for CIGS absorbers prepared by thermal evaporation, which has resulted in high-performing CIGS solar cells with PCEs up to 23.4% [14], and it has proven to be an effective strategy for enhancing performance, optimized for \u201csingle-junction\u201d CIGS; however, it has not been determined whether DG would be the ideal configuration for tandem applications. Kim et al. [15] used single-graded (SG) CIGS with a bandgap close to 1.0 eV, where the band grading is only formed on the backside of the absorber. They employed dual alkali post-deposition treatment (PDT) with KF and CsF, demonstrating a CIGS solar cell with a PCE of 20.<\/p>\n","protected":false},"excerpt":{"rendered":"

This study examined the potential of narrow-bandgap (Perovskite-based tandem solar cells are a promising photovoltaic (PV) technology to exceed the Shockley\u2013Queisser limit of single-junction solar cells. Perovskite\/Si tandem solar cells have been intensively studied, demonstrating a record power conversion efficiency (PCE) of 34.6% [1]. In contrast, the certified record PCE of perovskite\/Cu(In, Ga)Se2 (CIGS) tandem [\u2026]<\/p>\n","protected":false},"author":662,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[19,1633,17],"tags":[],"class_list":["post-238291","post","type-post","status-publish","format-standard","hentry","category-chemistry","category-solar-power","category-sustainability"],"_links":{"self":[{"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/posts\/238291","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/users\/662"}],"replies":[{"embeddable":true,"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/comments?post=238291"}],"version-history":[{"count":0,"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/posts\/238291\/revisions"}],"wp:attachment":[{"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/media?parent=238291"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/categories?post=238291"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/tags?post=238291"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}