In this study, we explore cocatalyst-free, single-crystalline, and epitaxial thin film zinc telluride (ZnTe) as a photocathode for CO2-to-CO conversion. The study systematically examines the impact of electronic properties and crystal orientation using nitrogen-doped, p-type ZnTe (ZnTe:N) photocathodes grown on GaAs substrates by molecular beam epitaxy (MBE). Heavily doped ZnTe:N ([p] ≅ 1020 cm–3) with a (100) orientation achieves a selective CO2-to-CO Faradaic efficiency of 62% over a 200-mV potential window (with current densities of ∼0.1 mA·cm–2) without additional surface modifications. ZnTe:N of (100), (110), and (111) crystal orientations demonstrate different photoactivity, with the (100) and (110) orientations exhibiting three times higher photocurrent density compared to the (111) orientation despite their similar electronic properties. Overall, this study provides a foundation for further development of ZnTe-based tandem devices for photoelectrochemical CO2 reduction.
", "doi": "10.1021/acsaem.5c03133", "issn": "2574-0962", "publisher": "American Chemical Society", "publication": "ACS Applied Energy Materials", "publication_date": "2026-03-23", "series_number": "6", "volume": "9", "issue": "6", "pages": "3005-3015" }, { "id": "authors:1wwyy-1et30", "collection": "authors", "collection_id": "1wwyy-1et30", "cite_using_url": "https://authors.library.caltech.edu/records/1wwyy-1et30", "type": "article", "title": "Dual carrier-selective contact transition metal dichalcogenide solar cells", "author": [ { "family_name": "Went", "given_name": "Cora M." }, { "family_name": "Tham", "given_name": "Rachel W.", "clpid": "Tham-Rachel-W" }, { "family_name": "Jahelka", "given_name": "Phillip R.", "orcid": "0000-0002-1460-7933", "clpid": "Jahelka-Phillip-R" }, { "family_name": "Wong", "given_name": "Joeson" }, { "family_name": "Mandigo-Stoba", "given_name": "Morgaine" }, { "family_name": "Atwater", "given_name": "Harry A.", "orcid": "0000-0001-9435-0201", "clpid": "Atwater-H-A" } ], "abstract": "Transition metal dichalcogenide (TMD) solar cells are promising candidates for high-specific-power photovoltaics due to their strong light-matter interactions, such as their high absorption coefficients. The performance of many TMD solar devices is limited by recombination losses at the semiconductor and metal electrode interface. Recent studies with silicon and perovskite solar cells overcome this challenge by employing two carrier-selective contacts to improve carrier separation and collection. In this work, we design and demonstrate the first dual selective contact TMD solar cell with both electron and hole transport layers. Resembling inverted perovskite device architectures, this solar cell consists of a vertical-junction 10-nm-thick WS2 absorber layer, C60 electron-selective contact, and PTAA hole-selective contact. This photovoltaic device exhibits an AM1.5 G open-circuit voltage of 523 mV and a power conversion efficiency of 2.4%. We characterize the carrier dynamics in the dual selective contact solar cell, which include achieving balanced transport with symmetric carrier-selective contact conductance to achieve high fill factors. We demonstrate this by showing that S-shaped I–V curves can be eliminated through reducing the thickness of the low-conductance contact. From theoretical calculations, we find that the TMD carrier lifetime limits the open-circuit voltage of TMD solar cells. To move towards the voltage limit and achieve higher solar performance, we outline steps for improving the dual selective contact solar cell architecture.
", "doi": "10.1038/s41699-026-00684-3", "issn": "2397-7132", "publisher": "Nature Publishing Group", "publication": "npj 2D Materials and Applications", "publication_date": "2026-03-12" }, { "id": "authors:9brt4-5mb24", "collection": "authors", "collection_id": "9brt4-5mb24", "cite_using_url": "https://authors.library.caltech.edu/records/9brt4-5mb24", "type": "article", "title": "Beyond Earth: Resilience of Quasi\u20102D Perovskite Solar Cells in Space", "author": [ { "family_name": "Putz", "given_name": "Christoph", "orcid": "0000-0003-2277-6363" }, { "family_name": "Lehner", "given_name": "Lukas E.", "orcid": "0000-0002-2273-6946" }, { "family_name": "Demchyshyn", "given_name": "Stepan", "orcid": "0000-0003-2089-7348" }, { "family_name": "Hailegnaw", "given_name": "Bekele", "orcid": "0000-0003-4427-2772" }, { "family_name": "Jahelka", "given_name": "Phillip", "orcid": "0000-0002-1460-7933", "clpid": "Jahelka-Phillip-R" }, { "family_name": "Breitwieser", "given_name": "Magdalena", "orcid": "0009-0003-9583-4859" }, { "family_name": "\u00d6zen", "given_name": "Sercan" }, { "family_name": "Denker", "given_name": "Andrea", "orcid": "0009-0000-5992-2403" }, { "family_name": "Bundesmann", "given_name": "J\u00fcrgen" }, { "family_name": "Dittwald", "given_name": "Alina Hanna", "orcid": "0009-0008-7633-4337" }, { "family_name": "Karabulut", "given_name": "Dilara" }, { "family_name": "Tockhorn", "given_name": "Philipp", "orcid": "0000-0003-1361-2252" }, { "family_name": "Albrecht", "given_name": "Steve", "orcid": "0000-0001-9962-9535" }, { "family_name": "Lang", "given_name": "Felix", "orcid": "0000-0001-9711-380X" }, { "family_name": "Scharber", "given_name": "Markus C.", "orcid": "0000-0002-4918-4803" }, { "family_name": "Kelzenberg", "given_name": "Michael D.", "orcid": "0000-0002-6249-2827", "clpid": "Kelzenberg-Michael-David" }, { "family_name": "Atwater", "given_name": "Harry A.", "orcid": "0000-0001-9435-0201", "clpid": "Atwater-H-A" }, { "family_name": "Kaltenbrunner", "given_name": "Martin", "orcid": "0000-0002-7247-9183" } ], "abstract": "Perovskite solar cells (PSCs) offer unique advantages for space\u2010based energy harvesting, combining cost\u2010effective manufacturing with flexible, high power\u2010to\u2010weight devices that can reduce payload mass in deployable structures. Despite this promise, few reports have demonstrated the viability of this technology in realistic, space\u2010based scenarios, where they are subjected to large temperature variations and hard radiation. Here, we present a comprehensive analysis of PSC performance in low Earth orbit (LEO). The champion rigid cell exhibited relatively stable in\u2010orbit performance at ∼80% of initial efficiency over a 44\u2010day measurement interval that concluded nearly 100 days after launch, corresponding to ∼1600 orbital eclipse cycles and temperature ranges from −25 to 35°C. Mission data was systematically compared with laboratory measurements of rigid and ultrathin flexible PSCs across temperatures from −80 to +80°C and upon exposure to high\u2010energy proton radiation. Flexible devices retained over 92% efficiency after a proton dose equivalent to 50 years in orbit. Despite this radiation tolerance, mitigating pre\u2010flight environmental degradation remains a challenge for ultrathin substrates. Combined, this study bridges the gap between short suborbital demonstrations and long\u2010term orbital performance, highlighting the potential of PSCs as a low\u2010cost, resilient alternative for light harvesting, even in harsh space environments.
", "doi": "10.1002/adma.202520433", "issn": "0935-9648", "publisher": "Wiley", "publication": "Advanced Materials", "publication_date": "2026-02-12", "pages": "e20433" }, { "id": "authors:ge1bv-rec88", "collection": "authors", "collection_id": "ge1bv-rec88", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220823-625642500.750", "type": "article", "title": "Integrated Solar-Driven Device with a Front Surface Semitransparent Catalysts for Unassisted CO\u2082 Reduction", "author": [ { "family_name": "Cheng", "given_name": "Wen\u2010Hui", "clpid": "Cheng-Wen\u2010Hui" }, { "family_name": "Richter", "given_name": "Matthias H.", "orcid": "0000-0003-0091-2045", "clpid": "Richter-Matthias-H" }, { "family_name": "M\u00fcller", "given_name": "Ralph", "clpid": "M\u00fcller-Ralph" }, { "family_name": "Kelzenberg", "given_name": "Michael", "orcid": "0000-0002-6249-2827", "clpid": "Kelzenberg-M-D" }, { "family_name": "Yalamanchili", "given_name": "Sisir", "clpid": "Yalamanchili-Sisir" }, { "family_name": "Jahelka", "given_name": "Phillip R.", "orcid": "0000-0002-1460-7933", "clpid": "Jahelka-Phillip-R" }, { "family_name": "Perry", "given_name": "Andrea N.", "clpid": "Perry-Andrea-N" }, { "family_name": "Wu", "given_name": "Pin Chieh", "orcid": "0000-0002-5781-9696", "clpid": "Wu-Pin-Chieh" }, { "family_name": "Saive", "given_name": "Rebecca", "orcid": "0000-0001-7420-9155", "clpid": "Saive-Rebecca" }, { "family_name": "Dimroth", "given_name": "Frank", "orcid": "0000-0002-3615-4437", "clpid": "Dimroth-Frank" }, { "family_name": "Brunschwig", "given_name": "Bruce S.", "orcid": "0000-0002-6135-6727", "clpid": "Brunschwig-B-S" }, { "family_name": "Hannappel", "given_name": "Thomas", "orcid": "0000-0002-6307-9831", "clpid": "Hannappel-Thomas" }, { "family_name": "Atwater", "given_name": "Harry A.", "orcid": "0000-0001-9435-0201", "clpid": "Atwater-H-A" } ], "abstract": "Monolithic integrated photovoltaic-driven electrochemical (PV-EC) artificial photosynthesis is reported for unassisted CO\u2082 reduction. The PV-EC structures employ triple junction photoelectrodes with a front mounted semitransparent catalyst layer as a photocathode. The catalyst layer is comprised of an array of microscale triangular metallic prisms that redirect incoming light toward open areas of the photoelectrode to reduce shadow losses. Full wave electromagnetic simulations of the prism array (PA) structure guide optimization of geometries and length scales. An integrated device is constructed with Ag catalyst prisms covering 35% of the surface area. The experimental device has close to 80% of the transmittance with a catalytic surface area equivalent 144% of the glass substrate area. Experimentally this photocathode demonstrates a direct solar-to-CO conversion efficiency of 5.9% with 50 h stability. Selective electrodeposition of Cu catalysts onto the surface of the Ag triangular prisms allows CO2 conversion to higher value products enabling demonstration of a solar-to-C\u2082\u208a product efficiency of 3.1%. This design featuring structures that have a semitransparent catalyst layer on a PV-EC cell is a general solution to light loss by shadowing for front surface mounted metal catalysts, and opens a route for the development of artificial photosynthesis based on this scalable design approach.", "doi": "10.1002/aenm.202201062", "issn": "1614-6832", "publisher": "Wiley", "publication": "Advanced Energy Materials", "publication_date": "2022-08-30", "pages": "Art. No. 2201062" }, { "id": "authors:4hwgs-3wh44", "collection": "authors", "collection_id": "4hwgs-3wh44", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220811-935557000", "type": "article", "title": "Integrated Solar\u2010Driven Device with a Front Surface Semitransparent Catalysts for Unassisted CO\u2082 Reduction", "author": [ { "family_name": "Cheng", "given_name": "Wen-Hui", "orcid": "0000-0003-3233-4606", "clpid": "Cheng-Wen-Hui" }, { "family_name": "Richter", "given_name": "Matthias H.", "orcid": "0000-0003-0091-2045", "clpid": "Richter-Matthias-H" }, { "family_name": "M\u00fcller", "given_name": "Ralph", "clpid": "M\u00fcller-Ralph" }, { "family_name": "Kelzenberg", "given_name": "Michael", "orcid": "0000-0002-6249-2827", "clpid": "Kelzenberg-Michael-D" }, { "family_name": "Yalamanchili", "given_name": "Sisir", "clpid": "Yalamanchili-Sisir" }, { "family_name": "Jahelka", "given_name": "Phillip R.", "orcid": "0000-0002-1460-7933", "clpid": "Jahelka-Phillip-R" }, { "family_name": "Perry", "given_name": "Andrea N.", "clpid": "Perry-Andrea-N" }, { "family_name": "Wu", "given_name": "Pin Chieh", "orcid": "0000-0002-5781-9696", "clpid": "Wu-Pin-Chieh" }, { "family_name": "Saive", "given_name": "Rebecca", "orcid": "0000-0001-7420-9155", "clpid": "Saive-Rebecca" }, { "family_name": "Dimroth", "given_name": "Frank", "orcid": "0000-0002-3615-4437", "clpid": "Dimroth-Frank" }, { "family_name": "Brunschwig", "given_name": "Bruce S.", "orcid": "0000-0002-6135-6727", "clpid": "Brunschwig-Bruce-S" }, { "family_name": "Hannappel", "given_name": "Thomas", "orcid": "0000-0002-6307-9831", "clpid": "Hannappel-Thomas" }, { "family_name": "Atwater", "given_name": "Harry A.", "orcid": "0000-0001-9435-0201", "clpid": "Atwater-H-A" } ], "abstract": "Monolithic integrated photovoltaic-driven electrochemical (PV-EC) artificial photosynthesis is reported for unassisted CO\u2082 reduction. The PV-EC structures employ triple junction photoelectrodes with a front mounted semitransparent catalyst layer as a photocathode. The catalyst layer is comprised of an array of microscale triangular metallic prisms that redirect incoming light toward open areas of the photoelectrode to reduce shadow losses. Full wave electromagnetic simulations of the prism array (PA) structure guide optimization of geometries and length scales. An integrated device is constructed with Ag catalyst prisms covering 35% of the surface area. The experimental device has close to 80% of the transmittance with a catalytic surface area equivalent 144% of the glass substrate area. Experimentally this photocathode demonstrates a direct solar-to-CO conversion efficiency of 5.9% with 50 h stability. Selective electrodeposition of Cu catalysts onto the surface of the Ag triangular prisms allows CO\u2082 conversion to higher value products enabling demonstration of a solar-to-C\u2082\u208a product efficiency of 3.1%. This design featuring structures that have a semitransparent catalyst layer on a PV-EC cell is a general solution to light loss by shadowing for front surface mounted metal catalysts, and opens a route for the development of artificial photosynthesis based on this scalable design approach.", "doi": "10.1002/aenm.202201062", "issn": "1614-6832", "publisher": "Wiley", "publication": "Advanced Energy Materials", "publication_date": "2022-08-12", "pages": "Art. No. 2201062" }, { "id": "authors:8f6ac-kxy25", "collection": "authors", "collection_id": "8f6ac-kxy25", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210917-215613739", "type": "article", "title": "Silicon Heterojunction Microcells", "author": [ { "family_name": "Potter", "given_name": "Maggie M.", "orcid": "0000-0002-6262-1078", "clpid": "Potter-Maggie-M" }, { "family_name": "Phelan", "given_name": "Megan E.", "orcid": "0000-0002-4968-7128", "clpid": "Phelan-Megan-E" }, { "family_name": "Balaji", "given_name": "Pradeep", "clpid": "Balaji-Pradeep" }, { "family_name": "Jahelka", "given_name": "Phillip", "orcid": "0000-0002-1460-7933", "clpid": "Jahelka-Phillip-R" }, { "family_name": "Bauser", "given_name": "Haley C.", "clpid": "Bauser-Haley-C" }, { "family_name": "Glaudell", "given_name": "Rebecca D.", "clpid": "Glaudell-Rebecca-D" }, { "family_name": "Went", "given_name": "Cora M.", "orcid": "0000-0001-7737-3348", "clpid": "Went-Cora-M" }, { "family_name": "Enright", "given_name": "Michael J.", "clpid": "Enright-Michael-J" }, { "family_name": "Needell", "given_name": "David R.", "orcid": "0000-0001-8343-5883", "clpid": "Needell-David-R" }, { "family_name": "Augusto", "given_name": "Andr\u00e9", "clpid": "Augusto-Andr\u00e9" }, { "family_name": "Atwater", "given_name": "Harry A.", "orcid": "0000-0001-9435-0201", "clpid": "Atwater-H-A" }, { "family_name": "Nuzzo", "given_name": "Ralph G.", "orcid": "0000-0003-2310-2045", "clpid": "Nuzzo-Ralph-G" } ], "abstract": "We report the design, fabrication, and characterization of silicon heterojunction microcells, a new type of photovoltaic cell that leverages high-efficiency bulk wafers in a microscale form factor, while also addressing the challenge of passivating microcell sidewalls to mitigate carrier recombination. We present synthesis methods exploiting either dry etching or laser cutting to realize microcells with native oxide-based edge passivation. Measured microcell performance for both fabrication processes is compared to that in simulations. We characterize the dependence of microcell open-circuit voltage (V_(oc)) on the cell area\u2013perimeter ratio and examine synthesis processes that affect edge passivation quality, such as sidewall damage removal, the passivation material, and the deposition technique. We report the highest Si microcell V_(oc) to date (588 mV, for a 400 \u03bcm \u00d7 400 \u03bcm \u00d7 80 \u03bcm device), demonstrate V_(oc) improvements with deposited edge passivation of up to 55 mV, and outline a pathway to achieve microcell efficiencies surpassing 15% for such device sizes.", "doi": "10.1021/acsami.1c11122", "issn": "1944-8244", "publisher": "American Chemical Society", "publication": "ACS Applied Materials & Interfaces", "publication_date": "2021-09-29", "series_number": "38", "volume": "13", "issue": "38", "pages": "45600-45608" }, { "id": "authors:xxw1c-9nr92", "collection": "authors", "collection_id": "xxw1c-9nr92", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200522-130424072", "type": "article", "title": "Controlling the dopant profile for SRH suppression at low current densities in \u03bb\u2009\u2248\u20091330\u2009nm GaInAsP light-emitting diodes", "author": [ { "family_name": "Santhanam", "given_name": "Parthiban", "orcid": "0000-0002-5250-8952", "clpid": "Santhanam-Parthiban" }, { "family_name": "Li", "given_name": "Wei", "orcid": "0000-0002-2227-9431", "clpid": "Li-Wei" }, { "family_name": "Zhao", "given_name": "Bo", "clpid": "Zhao-Bo" }, { "family_name": "Rogers", "given_name": "Chris", "clpid": "Rogers-Chris" }, { "family_name": "Gray", "given_name": "Dodd Joseph, Jr.", "orcid": "0000-0003-0469-599X", "clpid": "Gray-Dodd-Joseph-Jr" }, { "family_name": "Jahelka", "given_name": "Phillip", "orcid": "0000-0002-1460-7933", "clpid": "Jahelka-Phillip-R" }, { "family_name": "Atwater", "given_name": "Harry A.", "orcid": "0000-0001-9435-0201", "clpid": "Atwater-H-A" }, { "family_name": "Fan", "given_name": "Shanhui", "orcid": "0000-0002-0081-9732", "clpid": "Fan-Shanhui" } ], "abstract": "The quantum efficiency of double hetero-junction light-emitting diodes (LEDs) can be significantly enhanced at low current density by tailoring the spatial profile of dopants to suppress Shockley\u2013Read\u2013Hall recombination. To demonstrate this effect, we model, design, grow, fabricate, and test a GaInAsP LED (\u03bb\u2248 1330\u2009nm) with an unconventional dopant profile. Compared against that of our control design, which is a conventional n\u207a-n-p\u207a double hetero-junction LED, the dopant profile near the n-p\u207a hetero-structure of the design displaces the built-in electric field in such a way that the J\u2080\u2082 space charge recombination current is suppressed. The design principle generalizes to other material systems and could be applicable to efforts to observe and exploit electro-luminescent refrigeration at practical power densities.", "doi": "10.1063/5.0002058", "issn": "0003-6951", "publisher": "American Institute of Physics", "publication": "Applied Physics Letters", "publication_date": "2020-05-18", "series_number": "20", "volume": "116", "issue": "20", "pages": "Art. No. 203503" } ]